Merge bitcoindevkit/bdk#1477: feat(wallet): add transactions_sort_by function

83a0247e8ea6afd8329af5dd9b28f9892bd5e9c1 feat(wallet): add transactions_sort_by function (Steve Myers)

Pull request description:

  ### Description

  Added new type alias `WalletTx` which represents a `CanonicalTx<'a, Arc<Transaction>, ConfirmationTimeHeightAnchor>` and new `Wallet::transactions_sort_by` that returns a `Vec<WalletTx>` sorted by the given compare function.

  ### Notes to the reviewers

  fixes #794

  ### Changelog notice

  * Add new type alias `WalletTx` which represents a `CanonicalTx<'a, Arc<Transaction>, ConfirmationTimeHeightAnchor>`.
  * Add `Wallet::transactions_sort_by()` that returns a `Vec<WalletTx>` sorted by a given compare function.

  ### 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

Top commit has no ACKs.

Tree-SHA512: 5758b5edf8200b5534b7a7f538de640e85083bed3da2585109190f0efda3e238f5483d4a2dc073dc4b907644f58b7158a922ebe09d03a47201030162d4b0f4d3