Merge #20749: [Bundle 1/n] Prune g_chainman usage related to ::LookupBlockIndex

67c9a83df19c6e2a2edb32336879204e7770b4a7 style-only: Remove redundant sentence in ActivateBestChain comment (Carl Dong)
b8e95658d5909f93dfc7d1e6532661db8919e5b7 style-only: Make TestBlockValidity signature readable (Carl Dong)
0cdad753903640ff4240b715dec9d62f68e51407 validation: Use accessible chainstate in ChainstateManager::ProcessNewBlock (Carl Dong)
ea4fed90219be17160136313c68c06d84176af08 validation: Use existing chainstate in ChainstateManager::ProcessNewBlockHeaders (Carl Dong)
e0dc3057277c9576ddbfb8541599db0149e08bb6 validation: Move LoadExternalBlockFile to CChainState (Carl Dong)
5f8cd7b3a527999512161956db4d718688cb956f validation: Remove global ::ActivateBestChain (Carl Dong)
2a696472a1423e877bfa83f016f66c7e45be7369 validation: Pass in chainstate to ::NotifyHeaderTip (Carl Dong)
9c300cc8b3ce3d82874982fbf3087e48a6ac0ef2 validation: Pass in chainstate to TestBlockValidity (Carl Dong)
0e17c833cda67cdba5338bd7409061772b6d5edb validation: Make CChainState.m_blockman public (Carl Dong)
d363d06bf7d6c3736140672ba8a7f82f4d6fb6ab validation: Pass in blockman to ContextualCheckBlockHeader (Carl Dong)
f11d11600ddb0ddff6538250ae2a35df6112c3db validation: Move GetLastCheckpoint to BlockManager (Carl Dong)
e4b95eefbc700ebc915bec312f77477ce3e87a7e validation: Move GetSpendHeight to BlockManager (Carl Dong)
b026e318c39f59a06e29f1b25c7f577e01b25ccb validation: Move FindForkInGlobalIndex to BlockManager (Carl Dong)
3664a150ac7547c9336b571557af223d9e31aac9 validation: Remove global LookupBlockIndex (Carl Dong)
eae54e6e60d7ed05b29d8345c0bb055397149ce8 scripted-diff: Use BlockManager::LookupBlockIndex (Carl Dong)
15d20f40e1321b24963b40c12958c7d30ad112ec validation: Move LookupBlockIndex to BlockManager (Carl Dong)
f92dc6557a153b390a1ae1d0808ff7ed5d02c66e validation: Guard the active_chainstate with cs_main (Carl Dong)

Pull request description:

  Overall PR: #20158 (tree-wide: De-globalize ChainstateManager)

  Note to reviewers:
  1. This bundle may _apparently_ introduce usage of `g_chainman` or `::Chain(state|)Active()` globals, but these are resolved later on in the overall PR. [Commits of overall PR](https://github.com/bitcoin/bitcoin/pull/20158/commits)
  2. There may be seemingly obvious local references to `ChainstateManager` or other validation objects which are not being used in callers of the current function in question, this is done intentionally to **_keep each commit centered around one function/method_** to ease review and to make the overall change systematic. We don't assume anything about our callers. Rest assured that once we are considering that particular caller in later commits, we will use the obvious local references. [Commits of overall PR](https://github.com/bitcoin/bitcoin/pull/20158/commits)
  3. When changing a function/method that has many callers (e.g. `LookupBlockIndex` with 55 callers), it is sometimes easier (and less error-prone) to use a scripted-diff. When doing so, there will be 3 commits in sequence so that every commit compiles like so:
  1. Add `new_function`, make `old_function` a wrapper of `new_function`, divert all calls to `old_function` to `new_function` **in the local module only**
  2. Scripted-diff to divert all calls to `old_function` to `new_function` **in the rest of the codebase**
  3. Remove `old_function`

ACKs for top commit:
  jnewbery:
    utACK 67c9a83df19c6e2a2edb32336879204e7770b4a7
  laanwj:
    re-ACK 67c9a83df19c6e2a2edb32336879204e7770b4a7
  ryanofsky:
    Code review ACK 67c9a83df19c6e2a2edb32336879204e7770b4a7. Changes since last review:

Tree-SHA512: 8744aba2dd57a40cd2fedca809b0fe24d771bc60da1bffde89601999384aa0df428057a86644a3f72fbeedbc8b04db6c4fd264ea0db2e73c279e5acc6d056cbf

2 files changed, 10 insertions, 10 deletions

diff --git a/src/node/coinstats.cpp b/src/node/coinstats.cpp
index 02e50c4dbe..56113cb731 100644
--- a/src/node/coinstats.cpp
+++ b/src/node/coinstats.cpp
@@ -63,7 +63,7 @@ static bool GetUTXOStats(CCoinsView* view, CCoinsStats& stats, T hash_obj, const
     stats.hashBlock = pcursor->GetBestBlock();
     {
         LOCK(cs_main);
-        stats.nHeight = LookupBlockIndex(stats.hashBlock)->nHeight;
+        stats.nHeight = g_chainman.m_blockman.LookupBlockIndex(stats.hashBlock)->nHeight;
     }
 
     PrepareHash(hash_obj, stats);
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index e07eaa33d8..b7efd68cfd 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -447,7 +447,7 @@ public:
     {
         LOCK(cs_main);
         const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        if (CBlockIndex* fork = FindForkInGlobalIndex(active, locator)) {
+        if (CBlockIndex* fork = g_chainman.m_blockman.FindForkInGlobalIndex(active, locator)) {
             return fork->nHeight;
         }
         return nullopt;
@@ -456,7 +456,7 @@ public:
     {
         WAIT_LOCK(cs_main, lock);
         const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        return FillBlock(LookupBlockIndex(hash), block, lock, active);
+        return FillBlock(g_chainman.m_blockman.LookupBlockIndex(hash), block, lock, active);
     }
     bool findFirstBlockWithTimeAndHeight(int64_t min_time, int min_height, const FoundBlock& block) override
     {
@@ -468,7 +468,7 @@ public:
     {
         WAIT_LOCK(cs_main, lock);
         const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        if (const CBlockIndex* block = LookupBlockIndex(block_hash)) {
+        if (const CBlockIndex* block = g_chainman.m_blockman.LookupBlockIndex(block_hash)) {
             if (const CBlockIndex* ancestor = block->GetAncestor(ancestor_height)) {
                 return FillBlock(ancestor, ancestor_out, lock, active);
             }
@@ -479,8 +479,8 @@ public:
     {
         WAIT_LOCK(cs_main, lock);
         const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        const CBlockIndex* block = LookupBlockIndex(block_hash);
-        const CBlockIndex* ancestor = LookupBlockIndex(ancestor_hash);
+        const CBlockIndex* block = g_chainman.m_blockman.LookupBlockIndex(block_hash);
+        const CBlockIndex* ancestor = g_chainman.m_blockman.LookupBlockIndex(ancestor_hash);
         if (block && ancestor && block->GetAncestor(ancestor->nHeight) != ancestor) ancestor = nullptr;
         return FillBlock(ancestor, ancestor_out, lock, active);
     }
@@ -488,8 +488,8 @@ public:
     {
         WAIT_LOCK(cs_main, lock);
         const CChain& active = Assert(m_node.chainman)->ActiveChain();
-        const CBlockIndex* block1 = LookupBlockIndex(block_hash1);
-        const CBlockIndex* block2 = LookupBlockIndex(block_hash2);
+        const CBlockIndex* block1 = g_chainman.m_blockman.LookupBlockIndex(block_hash1);
+        const CBlockIndex* block2 = g_chainman.m_blockman.LookupBlockIndex(block_hash2);
         const CBlockIndex* ancestor = block1 && block2 ? LastCommonAncestor(block1, block2) : nullptr;
         // Using & instead of && below to avoid short circuiting and leaving
         // output uninitialized.
@@ -499,7 +499,7 @@ public:
     double guessVerificationProgress(const uint256& block_hash) override
     {
         LOCK(cs_main);
-        return GuessVerificationProgress(Params().TxData(), LookupBlockIndex(block_hash));
+        return GuessVerificationProgress(Params().TxData(), g_chainman.m_blockman.LookupBlockIndex(block_hash));
     }
     bool hasBlocks(const uint256& block_hash, int min_height, Optional<int> max_height) override
     {
@@ -511,7 +511,7 @@ public:
         // used to limit the range, and passing min_height that's too low or
         // max_height that's too high will not crash or change the result.
         LOCK(::cs_main);
-        if (CBlockIndex* block = LookupBlockIndex(block_hash)) {
+        if (CBlockIndex* block = g_chainman.m_blockman.LookupBlockIndex(block_hash)) {
             if (max_height && block->nHeight >= *max_height) block = block->GetAncestor(*max_height);
             for (; block->nStatus & BLOCK_HAVE_DATA; block = block->pprev) {
                 // Check pprev to not segfault if min_height is too low