Optimize OpenJDK VarHandle operation methods

[nbhuiyan]

VarHandle operation methods are mostly calls to Unsafe methods, which under certain circumstances can be folded into simple loads and stores in UnsafeFastPath as we can determine the object base and offsets at compile time. In other cases, we can unlock the fast paths for the Unsafe operations by setting the appropriate flags for CodeGen to inline the intrinsics if the platform supports the operations.

~In draft state while I perform further testing and performance investigations.~