[backport#18067] wallet: Improve LegacyScriptPubKeyMan::CanProvide script recognition
Summary:
a304a3632f0437f4d0f04589a2200e2da91624a7 Revert "Store p2sh scripts in AddAndGetDestinationForScript" (Russell Yanofsky)
eb7d8a5b07e89133a5fb465ad1b793362e7439f7 [test] check for addmultisigaddress regression (Sjors Provoost)
005f8a92ccb5bc10c8daa106d75e1c21390461d3 wallet: Improve LegacyScriptPubKeyMan::CanProvide script recognition (Russell Yanofsky)
Pull request description:
Make `LegacyScriptPubKeyMan::CanProvide` method able to recognize p2sh scripts when the redeem script is present in the `mapScripts` map without the p2sh script also having to be added to the `mapScripts` map. This restores behavior prior to #17261, which I think broke backwards compatibility with old wallet files by no longer treating addresses created by `addmultisigaddress` calls before #17261 as solvable. The reason why tests didn't fail with the CanProvide implementation in #17261 is because of a workaround added in 4a7e43e8460127a40a7895519587399feff3b682 "Store p2sh scripts in AddAndGetDestinationForScript", which masked the problem for new `addmultisigaddress` RPC calls without fixing it for multisig addresses already created in old wallet files. This change adds a lot of comments and allows reverting commit 4a7e43e8460127a40a7895519587399feff3b682 "Store p2sh scripts in AddAndGetDestinationForScript", so the `AddAndGetDestinationForScript()` function, `CanProvide()` method, and `mapScripts` map should all be more comprehensible
Backport of Core PR18067
Test Plan:
ninja all check check-functional
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Subscribers: PiRK
Differential Revision: https://reviews.bitcoinabc.org/D9115