Merge bitcoindevkit/bdk#1128: feat: add bdk_sqlite crate implementing PersistBackend

475c5024ecc5d288f35fabb8fab2b62dbf67653b feat(sqlite): add bdk_sqlite crate implementing PersistBackend backed by a SQLite database (Steve Myers)
b8aa76cd050bc3c2eac776ecbd9b4e2ab3e2590e feat(wallet): use the new `CombinedChangeSet` of `bdk_persist` (志宇)
0958ff56b20c1325a7da5d5f21e7ac836c601f1f feat(persist): introduce `CombinedChangeSet` (志宇)
54942a902d3203ee59731f35d2a1c402ac626878 ci: bump build_docs rust version to nightly-2024-05-12 (Steve Myers)
d975a48e7c519a703441e74058321021957b177f docs: update README MSRV pinning to match CI (Steve Myers)

Pull request description:

  ### Description

  Add "bdk_sqlite_store" crate implementing `PersistBackend` backed by a SQLite database.

  ### Notes to the reviewers

  In addition to adding a SQLite based `PersistenceBackend` this PR also:

  * add  `CombinedChangeSet` in `bdk_persist` and update `wallet` crate to use it.
  * updates the `wallet/tests` to also use this new sqlite store crate.
  * updates `example-crates/wallet_esplora_async` to use this new sqlite store crate.
  * fixes out of date README instructions for MSRV.
  * bumps the ci `build_docs` job to rust `nightly-2024-05-12`.

  ### Changelog notice

  Changed

  - Update Wallet to use CombinedChangeSet for persistence.

  Added

  - Add  CombinedChangeSet in bdk_persist crate.
  - Add bdk_sqlite crate implementing SQLite based PersistenceBackend storage for CombinedChangeSet.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

  #### New Features:

  * [x] I've added tests for the new feature
  * [x] I've added docs for the new feature

ACKs for top commit:
  evanlinjin:
    ACK 475c5024ecc5d288f35fabb8fab2b62dbf67653b

Tree-SHA512: 72565127994fbfff34d7359e1d36d6f13e552995bb7ea61dd38ba5329b0d15e500fa106214a83fd870f1017dc659ff1bb8fc71bc6aad0a793730ec7f23179d8c