[mlir][ods] Make Attr/Type def accessors match the dialect

The generated attribute and type def accessors are changed to match the setting on the dialect. Most importantly, "prefixed" will now correctly convert snake case to camel case (e.g. `weight_zp` -> `getWeightZp`)

Reviewed By: jpienaar

Differential Revision: https://reviews.llvm.org/D127688