Replace multi-loaderallocator hash implementation in MethodDescBackpatchInfo (#22285)

Replace multi-loaderallocator hash implementation in MethodDescBackpatchInfo (#22285)

* GCHeapHash
- Hashtable implementation for runtime use
- Implementation written in C++
- Data storage in managed heap memory
- Based on SHash design, but using managed memory

CrossLoaderAllocatorHash
- Hash for c++ Pointer to C++ pointer where the lifetimes are controlled by different loader allocators
 - Support for add/remove/visit all entries of 1 key/visit all entries/ remove all entries of 1 key
- Supports holding data which is unmanaged, but data items themselves can be of any size (key/value are templated types)

* Swap MethodDescBackpatchInfo to use the CrossLoaderAllocatorHash

* The MethodDescBackpatchCrst needs to be around an allocation
- Adjust the Crst so that it can safely be used around code which allocates
- Required moving its use out from within the EESuspend logic used in rejit