Merge bitcoin/bitcoin#21207: MOVEONLY: CWallet transaction code out of wallet.cpp/.h

c7bd584 MOVEONLY: CWallet transaction code out of wallet.cpp/.h (Russell Yanofsky)

Pull request description:

  This commit just moves function without making any changes. It can be reviewed with `git log -p -n1 --color-moved=dimmed_zebra`

  Motivation for this change is to make `wallet.cpp/h` less monolithic and start to make wallet transaction state tracking comprehensible so bugs in https://github.com/bitcoin-core/bitcoin-devwiki/wiki/Wallet-Transaction-Conflict-Tracking can be fixed safely without introducing new problems.

  This moves wallet classes and methods that deal with transactions out of `wallet.cpp/.h` into better organized files:

  - `transaction.cpp/.h` - CWalletTx and CMerkleTx class definitions
  - `receive.cpp/.h` - functions checking received transactions and computing balances
  - `spend.cpp/.h` - functions creating transactions and finding spendable coins

  After #20773, when loading is separated from syncing it will also be possible to move more `wallet.cpp/.h` functions to:

  - `sync.cpp/.h` - functions handling chain notifications and rescanning

  This commit arranges `receive.cpp` and `spend.cpp` functions in dependency order so it's possible to skim `receive.cpp` and get an idea of how computing balances works, and skim `spend.cpp` and get an idea of how transactions are created, without having to jump all over `wallet.cpp` where functions are not in order and there is a lot of unrelated code.

  Followup commit "refactor: Detach wallet transaction methods" in bitcoin/bitcoin#21206 follows up this PR and tweaks function names and arguments to reflect new locations. The two commits are split into separate PRs because this commit is more work to maintain and less work to review, while the other commit is less work to maintain and more work to review, so hopefully this commit can be merged earlier.

ACKs for top commit:
  Sjors:
    re-utACK c7bd584
  fjahr:
    utACK c7bd584
  promag:
    Code review ACK c7bd584, verified move only claim.
  meshcollider:
    Dimmed-zebra-check and functional test run ACK c7bd584

Tree-SHA512: 4981de6911cb1196774db375494355cc9af59b52456129c002d264a77cd9ed6175f8ecbb6b2f492a59a4d5a0def21a39d96fa79c9f4d99be0992985f553be32f

Author: meshcollider

src/Makefile.am

@@ -285,10 +285,13 @@ BITCOIN_CORE_H = \
   wallet/fees.h \
   wallet/ismine.h \
   wallet/load.h \
+  wallet/receive.h \
   wallet/rpcwallet.h \
   wallet/salvage.h \
   wallet/scriptpubkeyman.h \
+  wallet/spend.h \
   wallet/sqlite.h \
+  wallet/transaction.h \
   wallet/wallet.h \
   wallet/walletdb.h \
   wallet/wallettool.h \
@@ -406,9 +409,12 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/fees.cpp \
   wallet/interfaces.cpp \
   wallet/load.cpp \
+  wallet/receive.cpp \
   wallet/rpcdump.cpp \
   wallet/rpcwallet.cpp \
   wallet/scriptpubkeyman.cpp \
+  wallet/spend.cpp \
+  wallet/transaction.cpp \
   wallet/wallet.cpp \
   wallet/walletdb.cpp \
   wallet/walletutil.cpp \