Merge bitcoindevkit/bdk#1152: fix(wallet_esplora): missing_heights uses the graph...

b1461f05d05a0b9cf056a9604032468064ca1a05 fix(wallet_esplora): missing_heights uses the... ...graph update (Daniela Brozzoni)

Pull request description:

  Fixes #1151.

  When wallet_esplora_* was used to sync a wallet containing a transaction confirmed some time ago (more than 10-15 blocks ago), the transaction would be stuck in an "unconfirmed" state forever.

  At the first scan time, `update_local_chain` would just fetch the last 10 to 15 blocks (depending on the server used), and `tx_graph.missing_heights` wouldn't return the tx's confirmation block as it was called on the original, non-updated tx_graph.
  So, after the first scan, we would have a transaction in memory with an anchor that doesn't exist in our local_chain, and try_get_chain_position would return unconfirmed.

  When scanning again, missing_heights would find the missing anchor, but `update_local_chain` wouldn't include it as it's older than ASSUME_FINAL_DEPTH.

  The missing block would be downloaded every time, but never included in the local_chain, and the transaction would remain unconfirmed forever.

  Here we call missing_heights on the updated graph, so that it can correctly return the anchor height, and `update_local_chain` can fetch it and include it in the chain.

  ### Notes to the reviewers

  I'm not sure if this is the right approach, so I'm opening this PR to gather feedback. I still need to add tests, I'll do so once we decide if this is the right way to go or not.

  ### 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:

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

ACKs for top commit:
  evanlinjin:
    ACK b1461f05d05a0b9cf056a9604032468064ca1a05

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