Allow omitting the standard enum prefix
When StrictEnums is false, the following is now allowed:
- oneof_enum_value: VALUE_1
The following is always allowed:
- oneof_enum_value: PROTO2_TEST_ENUM_VALUE_1
Note that this does not impact 'encoding', which always produces protojson-compatible output.
Every change also requires a change to the json schema plugin. Protoyaml input has never been (and never needs to be) valid protojson. Only the output is normalized to be compatible.
Honestly, because there are no backwards compatibility issues, there should be no option. This change only changes what used to be an error in to an intuitive non-error case. If any option should be supported it is the option to specify which one you want the jsonschema plugin to suggest, which is external to this library.