Minor feature:
- CL/589336: gofeatures: allow setting legacy_unmarshal_json_enum feature at file level
Minor bug fixes:
- CL/588875: types/descriptorpb: regenerate using latest protobuf v27.0 release
- CL/586396: internal/impl: fix size cache semantics with lazy decoding
- CL/585736: reflect/protodesc: remove obsolete JSON name check from desc validator
- CL/588976: reflect/protoreflect: FieldDescriptor.Kind should never be GroupKind for maps or fields of map entry