Attach `Method` to matched `XlaCallModuleOp`.
Attach `Method` to matched `XlaCallModuleOp`.

With this change, matched `XlaCallModuleOp` will carry the corresponding `Method` as an attribute, set within `LiftQuantizableSpotsAsFunctionsPass`.
This will help locally reason about the quantization method to apply to each `XlaCallModuleOp` in the downstream passes (e.g. `QuantizePass`).
