Merge bitcoin/bitcoin#26606: wallet: Implement independent BDB parser

d51fbab4b3 wallet, test: Be able to always swap BDB endianness (Ava Chow)
0b753156ce test: Test bdb_ro dump of wallet without reset LSNs (Ava Chow)
c1984f1282 test: Test dumping dbs with overflow pages (Ava Chow)
fd7b16e391 test: Test dumps of other endian BDB files (Ava Chow)
6ace3e953f bdb: Be able to make byteswapped databases (Ava Chow)
d9878903fb Error if LSNs are not reset (Ava Chow)
4d7a3ae78e Berkeley RO Database fuzz test (TheCharlatan)
3568dce9e9 tests: Add BerkeleyRO to db prefix tests (Ava Chow)
70cfbfdadf wallettool: Optionally use BERKELEY_RO as format when dumping BDB wallets (Ava Chow)
dd57713f6e Add MakeBerkeleyRODatabase (Ava Chow)
6e50bee67d Implement handling of other endianness in BerkeleyRODatabase (Ava Chow)
cdd61c9cc1 wallet: implement independent BDB deserializer in BerkeleyRODatabase (Ava Chow)
ecba230979 wallet: implement BerkeleyRODatabase::Backup (Ava Chow)
0c8e728476 wallet: implement BerkeleyROBatch (Ava Chow)
756ff9b478 wallet: add dummy BerkeleyRODatabase and BerkeleyROBatch classes (Ava Chow)
ca18aea5c4 Add AutoFile::seek and tell (Ava Chow)

Pull request description:

  Split from #26596

  This PR adds `BerkeleyRODatabase` which is an independent implementation of a BDB file parser. It provides read only access to a BDB file, and can therefore be used as a read only database backend for wallets. This will be used for dumping legacy wallet records and migrating legacy wallets without the need for BDB itself.

  Wallettool's `dump` command is changed to use `BerkeleyRODatabase` instead of `BerkeleyDatabase` (and `CWallet` itself) to demonstrate that this parser works and to test it against the existing wallettool functional tests.

ACKs for top commit:
  josibake:
    reACK d51fbab4b3
  TheCharlatan:
    Re-ACK d51fbab4b3
  furszy:
    reACK d51fbab4b3
  laanwj:
    re-ACK d51fbab4b3
  theStack:
    ACK d51fbab4b3

Tree-SHA512: 1e7b97edf223b2974eed2e9eac1179fc82bb6359e0a66b7d2a0c8b9fa515eae9ea036f1edf7c76cdab2e75ad994962b134b41056ccfbc33b8d54f0859e86657b

test/functional/test_runner.py

@@ -183,6 +183,8 @@ BASE_SCRIPTS = [
     'mempool_resurrect.py',
     'wallet_txn_doublespend.py --mineblock',
     'tool_wallet.py --legacy-wallet',
+    'tool_wallet.py --legacy-wallet --bdbro',
+    'tool_wallet.py --legacy-wallet --bdbro --swap-bdb-endian',
     'tool_wallet.py --descriptors',
     'tool_signet_miner.py --legacy-wallet',
     'tool_signet_miner.py --descriptors',