Improvements to quantization matching code:

- Guarantee that we do the largest matches first.
- Don't allow matching layers multiple times.
- Don't allow adding quantization ops to the same node multiple times.
- Return a list of match results rather than yielding. This is much easier to reason about.
- Only require ReadVariableOp when matching resource variables, since the input to ReadVariableOps don't necessarily have to be a VarHandleOp.
- Place post activation bypass ops quantization nodes in the same post activation bypass op's name scope for better viewing.

PiperOrigin-RevId: 190169622