Merge bitcoindevkit/bdk#894: Better no-std support

7ab84be9c747fd73fc5d1bd0706e7027a66aadb5 Better no-std support (Steve Myers)

Pull request description:

  This replaces #893

  ### Description

  Carrying over relevant maintenance changes from release 0.27.2 to bdk `master`.

  - Use `default-features = false` for `miniscript` and `bitcoin`
  - Introduce `std`  features for `bdk`, `bdk_chain` and `bdk_esplora`

  ### Notes to the reviewers

  The `default-features = false`for `bitcoin` and `miniscript` is to let `bdk` be unbiased for things like no-std.

  ### Changelog notice

  - Set default-features = false for rust-bitcoin and rust-miniscript #894
  - Introduce `std`  features for `bdk`, `bdk_chain` and `bdk_esplora`

  ### 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 7ab84be9c747fd73fc5d1bd0706e7027a66aadb5

Tree-SHA512: 217e0ebc04cd59898d4de1c4f8cc6c87de2561659e277cc6e0d969c8bc61142ca62c8bda86643d55676dce39da25891b516a901005a03a31404dae118a5fce76