Merge bitcoindevkit/bdk#667: Rename `set_current_height` to `current_height`

92b9597f8b8dc3694508062b5e7c5f23acbc3a4f Rename `set_current_height` to `current_height` (Alekos Filini)

Pull request description:

  ### Description

  Usually we don't have any prefix except for methods that can *add* to a list or replace the list entirely (e.g. `add_recipients` vs `set_recipients`)

  I missed this during review of #611

  ### 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:
  danielabrozzoni:
    utACK 92b9597f8b8dc3694508062b5e7c5f23acbc3a4f - I'm sorry I didn't notice it!

Tree-SHA512: 3391068b2761bcd04d740ef41f9e772039fca7bc0e0736afcbc582ec74b6c91eb155d9e09dd7a07462eec29e32ac86e41ba339d9a550af3f754164cab6bdbf61