32912eaa05fd3bb4fa1577ca413dcedf909544d9 Don't default to use `async`/`await` on `wasm32` (Elias Rohrer)
Pull request description:
### Description
We don't automatically want to make the interface `async` based on the used architecture, but now require the user to explicitly set the `async-interface` feature.
#### 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:
notmandatory:
ACK 32912eaa05fd3bb4fa1577ca413dcedf909544d9
Tree-SHA512: 41a8f3ab29508a359a8c0d96994e4fa97e52c15e8b8003c1988bcfe036cafa81d6210d446ed825672ce52aff684ebb328dc61b8ae3d25cda6f51a3cae838de58
41dc7f7d0d