[HIP] Refactor HIP pointer type detection

[GeorgeWeb]

(This is currently a WIP) TODO: Add description and explanation of the changes in this refactor.

TODO: Revisit this making a simpler helper getUSMHostOrDevicePtr function internal to enqueue.cpp, turning the *Result<...> PointerTypeOrInvalid helper function into a bool IsSystemHostPointer helper (that can be used in other enqueue entry points).