Verify peripheral configuration support inline instead of seperate `has_` functions?

Throughout the crate I believe most (if not all) register-mutating functions are unchecked, meaning that the crate user should check for support before enabling and configurating a feature. I consider this reasonable for trivial functions such as DWT::has_exception_trace and DWT::enable_exception_tracing but less so for more complex functions like DWT::configure and ITM::configure which may enable and configure a whole set of features. For these functions it's not trivial to figure out which has_ functions must be called before configuration (presuming they are implemented in the first place).

I believe it would be a better idea to verify support in configure functions before registers are mutated (and return Err if the requested configuration cannot be applied) and offer some configure_unchecked variant when the user knows when a set of features are supported. I'm not sure if we should do the same to the more drivial functions.

Thoughts?

Start by reviewing the existing DWT::configure, ITM::configure, and related has_ functions to understand their current support checks and register mutations. Then determine the intended error and unchecked-variant API, including whether simpler functions should change; the issue is complete only after that behavior and scope are agreed and covered by appropriate tests.