1b7c6df569a0ff9324bbda1f066938490109481d fix(export): add tr descriptor (rustaceanrob)
Pull request description:
### Description
Resolves#860 by adding export of taproot descriptors
### Notes to the reviewers
Allows export as Core accepts taproot.
### Changelog notice
- Export taproot descriptors
### 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
#### New Features:
* [x] I've added tests for the new feature
* [ ] I've added docs for the new feature
#### Bugfixes:
* [ ] 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:
notmandatory:
ACK 1b7c6df569a0ff9324bbda1f066938490109481d
Tree-SHA512: 80bee93a1ec531717e79a5e7a91e840532ae4d3daf677a207bc53162c69410e47db4893024b3eccfd848f1628062e7c49f0e92ebeb7230e2ebb9b47eb84b9e56
a2d940132d