Merge #6543: backport: merge bitcoin#15596, bitcoin#21207, partial bitcoin#22155 (wallet refactoring)

2c3d9cf merge bitcoin#21207: CWallet transaction code out of wallet.cpp/.h (Kittywhiskers Van Gogh)
a21691a partial bitcoin#22155: Add test for subtract fee from recipient behavior (Kittywhiskers Van Gogh)
829510c merge bitcoin#15596: Ignore sendmany::minconf as dummy value (Kittywhiskers Van Gogh)

Pull request description:

  ## Additional Information

  As [dash#6517](#6517) and [dash#6529](#6529) both introduce behavior changes and workarounds that, changes from both PRs that do not affect behavior have been extracted and spun-off into this PR and they will be subsequently rebased on this PR upon merger into `develop`. This should let us at least get some of the larger (mostly move-only) diffs merged in and ease review for the aforementioned PRs.

  [bitcoin#21207](bitcoin#21207) can be reviewed using `git log -p -n1 --color-moved=dimmed_zebra`

  ## Breaking Changes

  None expected, no changes in behavior.

  ## Checklist

  - [x] I have performed a self-review of my own code
  - [x] I have commented my code, particularly in hard-to-understand areas **(note: N/A)**
  - [x] I have added or updated relevant unit/integration/functional/e2e tests
  - [x] I have made corresponding changes to the documentation **(note: N/A)**
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK 2c3d9cf
  PastaPastaPasta:
    utACK 2c3d9cf

Tree-SHA512: 3e5bb5869793b389aefbe0e97b1cedd13d06abce2ad06d1c16c0f8ecd4e0fa7f148fa5d89653c76ac97171787b35525ec20ece1ea753fb97eebec95a456411e2

Author: PastaPastaPasta

src/Makefile.am

@@ -401,10 +401,13 @@ BITCOIN_CORE_H = \
   wallet/hdchain.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 \
@@ -596,9 +599,12 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/hdchain.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 \

src/Makefile.test.include

@@ -213,6 +213,8 @@ endif
 
 
 BITCOIN_TEST_SUITE += \
+  wallet/test/util.cpp \
+  wallet/test/util.h \
   wallet/test/wallet_test_fixture.cpp \
   wallet/test/wallet_test_fixture.h \
   wallet/test/init_test_fixture.cpp \