e51af49ffa951e14203ac2b465ade351dd90f6cd fix(wallet): remove generic from wallet (Rob N)
Pull request description:
### Description
The `PersistenceBackend` uses generics to describe errors returned while applying the change set to the persistence layer. This change removes generics wherever possible and introduces a new public error enum. Removing the generics from `PersistenceBackend` errors is the first step towards #1363
*Update*: I proceeded with removing the generics from `Wallet` by introducing a `Box<dyn PersistenceBackend>` .
### Notes to the reviewers
This one sort of blew up in the number of changes due to the use of generics for most of the `Wallet` error variants. The generics were only used for the persistence errors, so I removed the generics from higher level errors whenever possible. The error variants of `PersistenceBackend` may also be more expressive, but I will level that up for discussion and make any changes required.
### Changelog notice
- Changed `PersistenceBackend` errors to depend on the `anyhow` crate.
- Remove the generic `T` from `Wallet`
### 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:
* [ ] I've added tests for the new feature
* [x] I've added docs for the new feature
#### Bugfixes:
* [x] This pull request breaks the existing API
* [ ] I've added tests to reproduce the issue which are now passing
* [x] I'm linking the issue being fixed by this PR
ACKs for top commit:
evanlinjin:
ACK e51af49ffa951e14203ac2b465ade351dd90f6cd
Tree-SHA512: 8ce4f1c495310e16145555f4a6a29a0f42cf8944eda68004595c3532580767f64f779185022147a00d75001c40d69fdf8f8de2d348eb68484b170d2a181117ff
f00de9e0c1