[mlir][DeclareOpInterfaceMethods] Allow specifying a set of methods to force...

[mlir][DeclareOpInterfaceMethods] Allow specifying a set of methods to force declaration generation for.

Currently a declaration won't be generated if the method has a default implementation. Meaning that operations that wan't to override the default have to explicitly declare the method in the extraClassDeclarations. This revision adds an optional list parameter to DeclareOpInterfaceMethods to allow for specifying a set of methods that should always have the declarations generated, even if there is a default.

Differential Revision: https://reviews.llvm.org/D79030