[mlir][Interfaces] Optimize the implementation of InterfaceMap to reduce generated...

[mlir][Interfaces] Optimize the implementation of InterfaceMap to reduce generated code size.

An InterfaceMap is generated for every single operation type, and is responsible for a large amount of the code size from MLIR given that its internals highly utilize templates. This revision refactors the internal implementation to use bare malloc/free for interface instances as opposed to static variables and moves as much code out of templates as possible. This led to a decrease of over >1mb (~12% of total MLIR related code size) for a downstream MLIR library with a large amount of operations.

Differential Revision: https://reviews.llvm.org/D90086