Merge bitcoin/bitcoin#27307: wallet: track mempool conflicts with wallet transactions

5952292133d6cc889f51ae771f2e0557311e1efe wallet, rpc: show mempool conflicts in `gettransaction` result (ishaanam)
54e07ee22ff16fc68583ade0d2b8ffffc81d444a wallet: track mempool conflicts (ishaanam)
d64922b5903e5ffc8d2ce0e6761f99f173b60800 wallet refactor: use CWalletTx member functions to determine tx state (ishaanam)
ffe5ff1fb622a8da11b66289e1b778e45e449811 scripted-diff: wallet: s/TxStateConflicted/TxStateBlockConflicted (ishaanam)
180973a94180f9849bf7cb0dab7c9177a942efb8 test: Add tests for wallet mempool conflicts (ishaanam)

Pull request description:

  The `mempool_conflicts` variable is added to `CWalletTx`, it is a set of txids of txs in the mempool conflicting with the wallet tx or a wallet tx's parent. This PR only changes how mempool-conflicted txs are dealt with in memory.

  `IsSpent` now returns false for an output being spent by a mempool conflicted transaction where it previously returned true.

  A txid is added to `mempool_conflicts` during  `transactionAddedToMempool`. A txid is removed from `mempool_conflicts` during  `transactionRemovedFromMempool`.

  This PR also adds a `mempoolconflicts` field to the `gettransaction` wallet RPC result.

  Builds on #27145
  Second attempt at #18600

ACKs for top commit:
  achow101:
    ACK 5952292133d6cc889f51ae771f2e0557311e1efe
  ryanofsky:
    Code review ACK 5952292133d6cc889f51ae771f2e0557311e1efe. Just small suggested changes since last review
  furszy:
    ACK 59522921

Tree-SHA512: 615779606723dbb6c2e302681d8e58ae2052ffee52d721ee0389746ddbbcf4b4c4afacf01ddf42b6405bc6f883520524186a955bf6b628fe9b3ae54cffc56a29

0 files changed, 0 insertions, 0 deletions