feat: expose TxBuilder coin selection

[reez]

Description

Exposes TxBuilder::coin_selection so people can choose the wallet coin selection algo when building transactions.

Notes to the reviewers

Looking for feedback on if we think this is something we want to do or not

Documentation

• bdk_wallet
  https://docs.rs/bdk_wallet/3.0.0/bdk_wallet/struct.TxBuilder.html#method.coin_selection
• bitcoin
• uniffi
• Other:

Changelog

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing
• I've added exactly one changelog:* label
• I've linked the relevant upstream docs or specs above

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR

[reez]

reviewable+rebased

[thunderbiscuit]

ACK 9f9233a.

It took me a bit of time to dig in and understand the requirement for the new method but I suspected an issue with the generics of the coin selection algo, which was indeed the case.

Thanks for adding this!

My only little thing I would like to have somewhere in the API docs is a statement of which coin selection is used if none is defined. We could maybe add it to the new enum?

I'll open an issue on the Rust side to bring that up as well.

[reez]

rebased