Merge bitcoin/bitcoin#26418: Fix signing of multi_a and rawtr scripts with wallets that only have corresponding keys

0de30ed509a9969cb254e00097671625c9e107d2 tests: Test Taproot PSBT signing with keys in other descriptor (Andrew Chow)
6efcdf6b7f6daa83b5937aa630fce358fdaed333 tests: Use new wallets for each test in wallet_taproot.py (Andrew Chow)
8781a1b6bbd0af3cfdf1421fd18de5432494619a psbt: Include output pubkey in additional pubkeys to sign (Andrew Chow)
323890d0d7db2628f9dc6eaeba6e99ce0a12e1f5 sign: Fill in taproot pubkey info for all script path sigs (Andrew Chow)

Pull request description:

  A user reported on [stackexchange](https://bitcoin.stackexchange.com/q/115742/48884) that they were unable to sign for a `multi_a` script using a wallet that only had the corresponding keys (i.e. it did not have the `multi_a()` descriptor). This PR fixes this issue.

  Additionally, `wallet_taproot.py` is modified to test for this scenario by having another wallet in `do_test_psbt` which contains descriptors that only have the keys involved in the descriptor being tested. `wallet_taproot.py` was also modified to create new wallets for each test case rather than sharing wallets throughout as the sharing could result in the signing wallet having the keys in a different descriptor and accidentally result in failing to detect a test failure.

  The changes to the test also revealed a similar issue with `rawtr()` descriptors, which has also been fixed by checking if a descriptor can produce a `SigningProvider` for the Taproot output pubkey.

ACKs for top commit:
  instagibbs:
    crACK https://github.com/bitcoin/bitcoin/pull/26418/commits/0de30ed509a9969cb254e00097671625c9e107d2
  darosior:
    ACK 0de30ed509a9969cb254e00097671625c9e107d2

Tree-SHA512: 12e131dd8afd93da7b1288c9054de2415a228d4477b97102da3ee4e82ce9de20b186260c3085a4b7b067bd8b74400751dcadf153f113db83abc59e7466e69f14

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