Merge bitcoindevkit/bdk#1562: fix(wallet)!: make `LoadParams` implicitly satisfy...

Merge bitcoindevkit/bdk#1562: fix(wallet)!: make `LoadParams` implicitly satisfy `Send`

295b9794caf142707c49666529268197694534e7 fix(wallet)!: make `LoadParams` implicitly satisfy `Send` (志宇)

Pull request description:

  ### Description

  Make `LoadParams` implicitly satisfy `Send`. This will hopefully make `AsyncWalletPersister` easier to implement.

  Refer to the [conversation on Discord](https://discord.com/channels/753336465005608961/753367451319926827/1273667818528964714).

  cc. @matthiasdebernardini

  ### Notes to the reviewers

  This is a breaking change, since we are tightening the bounds to some methods.

  ### Changelog notice

  * Change `LoadParams` to implicitly satisfy `Send`.

  ### 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

ACKs for top commit:
  LLFourn:
    ACK 295b9794caf142707c49666529268197694534e7
  notmandatory:
    ACK 295b9794caf142707c49666529268197694534e7

Tree-SHA512: 952cd7fbb058166af93af0b8afa3e0f3c1afe600f5782364da8e3c74e7388ca682bab34e2c60b221055e25ade2f6ddb4a2e9451d6d181f14b0bcca053522155c