[mlir][ods] Allow filtering of ops
Add option to filter which op the OpDefinitionsGen run on. This enables having multiple ops together in the same TD file but generating different CC files for them (useful if one wants to use multiclasses or split out 1 dialect into multiple different libraries). There is probably more general query here (e.g., split out all ops that don't have a verify method, or that are commutative) but filtering based on op name (e.g., test.a_op) seemed a reasonable start and didn't require inventing a query specification mechanism here.
Differential Revision: https://reviews.llvm.org/D82319