[mlir][Linalg] Further improve codegen strategy and add a linalg.matmul_i8_i8_i32

This revision adds a layer of SFINAE to the composable codegen strategy so it does
not have to require statically defined ops but instead can also be used with OpInterfaces, Operation* and an op name string.

A linalg.matmul_i8_i8_i32 is added to the .tc spec to demonstrate how all this works end to end.

Differential Revision: https://reviews.llvm.org/D95600