Merge bitcoindevkit/bdk#1490: Remove usage of `blockdata::` from bitcoin paths

cf7aca84d113e639441350651112e9e701364497 Remove usage of blockdata:: from bitcoin paths (Tobin C. Harding)

Pull request description:

  ### Description

  In `rust-bitcoin` the `blockdata` module is a code organisation thing, it should never have been public. One day those guys would like to remove it, so as not to be a PITA for `bdk` when they do lets remove all usage of `blockdata::` now.

  ### Changelog notice

  Internal change only, no externally visible changes.

  ### 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

Top commit has no ACKs.

Tree-SHA512: 4c5e54a2ac3f71835c25ce97ad0acd1859e5ae8d45ebfde087e19e9494754e0aa70a47ca5f3d6a3b509f27e28ef9d4a5269573c686250f43834d09378155681c