Merge bitcoindevkit/bdk#770: Upgrade to rust-bitcoin 0.29

c7a43d941fd0f457f615f2fe43e71586a253e46a Remove unused code (Alekos Filini)
1ffd59d469ff28f673d854eaf15c992c15541bfe Upgrade to rust-bitcoin 0.29 (Alekos Filini)
ae4f4e541671e85be04fdddc97cb7f65af1eeea1 Upgrade `rand` to `0.8` (Alekos Filini)
9854fd34eaa688e5acd601119b8f448a2d77fbd9 Remove deprecated address validators (Alekos Filini)

Pull request description:

  ### Description

  Upgrade BDK to rust-bitcoin 0.29

  Missing pieces:

  - [x] rust-miniscript `update_output_with_descriptor` - rust-bitcoin/rust-miniscript#465
  - [x] rust-miniscript 8.0.0 release - rust-bitcoin/rust-miniscript#462
  - [x] Upgrade rust-hwi to bitcoin 0.29 bitcoindevkit/rust-hwi#50
  - [x] Upgrade esplora-client to bitcoin 0.29 https://github.com/bitcoindevkit/rust-esplora-client/pull/20
  - [x] Upgrade rand to 0.8 like secp256k1 did

  ### Notes to the reviewers

  The commits still need to be reordered and cleaned up

  ### Changelog notice

  - Upgrade rust-bitcoin to 0.29
  - Remove deprecated "address validators"

  ### 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:
  notmandatory:
    ACK c7a43d941fd0f457f615f2fe43e71586a253e46a

Tree-SHA512: 718a1baf3613b31ec1de39fe63467ebee38617963a4ce0670a617e20fe4f46a57c5786933cdde6cfad9fc76ce0af08843f58844fb4a89f5948cb42c697f802ef