[mlir][ods] Add Deprecate helper

Add method to tag classes/defs as deprecated. Previously deprecations
were only verbally communicated and folks didn't have an active warning
while building about impending removal. Add mechanism to tag defs as
deprecated to allow warning users.

This doesn't change any policy, it just moves deprecation warnings from
comments to something more user visible.

Differential Revision: https://reviews.llvm.org/D122164