Merge bitcoindevkit/bdk#800: fix: ensure the key network is updated in the KeyMap...

150f4d6f41427d5d8a6608e7da4f30dfe3d0801a fix: ensure the key network is updated in the KeyMap as well (Alekos Filini)

Pull request description:

  ### Description

  Otherwise we may have inconsistencies with keys in the descriptor that have a network and keys in the keymap that are different.

  ### Notes to the reviewers

  Adding it to the `0.25` milestone since it's just a quick fix

  ### 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

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [x] I've added tests to reproduce the issue which are now passing
  * [ ] I'm linking the issue being fixed by this PR

ACKs for top commit:
  notmandatory:
    ACK 150f4d6f41427d5d8a6608e7da4f30dfe3d0801a

Tree-SHA512: df87323cc29cf74f54a0867bfbe9fe24543de69dc6443656bd920458c9055d4b05614430c89bb470a8a6f7d10da023a0fb107b1cfb0fcc38e50f0579b6411a33