Describe the enhancement

We should move bdk_hwi from the bdk repo crates and include it with to the hwi crate.

Use case

Removing bdk_hwi will simplify the bdk workspace and ci testing because we won't need to use pyo3.

Additional context

If we determine no one is using the hwi module we can more easily deprecate both hwi and bdk_hwi when they're together in the same crate. But also they will be together in case someone does want to use and maintain them.