…sed (#705)

* Delete `StoreRawSchema` from `GeneratorConfig` since it's not being used

I don't see the value of why we need this flag: is it to save memory?
For `exampleoc` this variable took 27MB, a negligible amount.

* Reorganize Code Generation flags and Delete `ygen.GeneratorConfig` (#706)

* ygen now only has `IROptions`.
* `CodeGenerator` in gogen/protogen now carry IROptions and their language-specific post-IR generation options.
* Code generation specific flags that are not used during IR generation are moved to `gogen` and `protogen`, duplicating if used by both (e.g. CallerName).
* `SkipEnumDeduplication` is moved from ParseOptions to TransformationOptions.