Merge bitcoindevkit/bdk#1737: fix(tx_builder)!: make TxBuilder Send safe, remove...

663fb133a4aeac7e50f5d32bdba2b316b17a7e2b fix(tx_builder)!: make TxBuilder Send safe, remove Clone trait (Steve Myers)

Pull request description:

  ### Description

  Inspired by discord chat with @stevenroose as a way to make the `TxBuilder` Send safe.

  See his original patch on 1.0.0-beta.5: https://gist.github.com/stevenroose/f7736dfedfaa64bbdbb0da5875df28fc

  ### Notes to the reviewers

  I had to remove the `Clone` trait on `TxBuilder` but it was only being used in tests.

  ### Changelog notice

  - TxBuilder is now Send safe and does not implement the Clone trait

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

ACKs for top commit:
  evanlinjin:
    ACK 663fb133a4aeac7e50f5d32bdba2b316b17a7e2b

Tree-SHA512: 026c0f5f227b5613bbab069b2c5238266aea6f6c2ae184cf77d37777fee2ddd52a99c9e305c107a2edd855dbd182d1b9194de361703995732061649f155cb65f

diff --cc crates/wallet/src/wallet/mod.rs
Simple merge

diff --cc crates/wallet/src/wallet/tx_builder.rs
Simple merge

diff --cc crates/wallet/tests/wallet.rs
Simple merge