[local gc] refactor apis for threading and suspension to avoid redundant calls in...

[local gc] refactor apis for threading and suspension to avoid redundant calls in to the runtime (#16765)

* [Local GC] Refactor calls involving thread modes, suspension, and alloc contexts to always operate on current thread

* BOOL -> bool for enable/disable preemptive routines, also remove an unused call to GetThread

* avoid one indirection by having GCToEEInterface::EnablePreemptiveGC return a bool indicating whether the mode was changed

* Callback on IGCHeap for the runtime to notify the GC when it is trapping threads

* use g_fSuspensionPending instead of GCToEEInterface::CatchAtSafePoint for allow_fgc

* Remove CatchAtSafePoint

* Remove GetThread from WaitLongerNoInstru

* code review feedback

* code review feedback

* change BOOL to bool