Merge bitcoindevkit/bdk#1495: example: Update `example_cli` and retire old nursery...

771f6b9c97a70be2e8d2da5216f3b686295861bd example: Update example_cli (valued mammal)

Pull request description:

  - Adds two commands `init` and `generate`. Loading database doesn't require descriptors
  - Replaces `send` command with `psbt` (new, sign, and extract). Supports tap key spend
  - Uses `bdk-coin-select` and miniscript `plan` module

  fixes #1469
  partially addresses #1462

  ### Notes to the reviewers

  Note the `example_cli` lib now defines the `ChangeSet` and `Anchor` type whereas before these were generic

  ### Changelog notice

  * Improvements to `example_cli` that include generating descriptors and creating PSBTs

  ### 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:
  evanlinjin:
    ACK 771f6b9c97a70be2e8d2da5216f3b686295861bd

Tree-SHA512: 93b9e38ec428c3ed5920e7632381dcf50e28a01ceb8e1438c87aa459563600cd79636bcf1179eefa763adce98239a60ad2894dfb2ba0f2700cc64e57ede75010