Due to the orphan rule, this meant removing our usages of impl ProtoStruct,
or converting them to a trait when they were used commonly.
rslib now directly references anki_proto and anki_i18n, instead of
'pub use'-ing them, and we can put the generated files back in OUT_DIR.
A couple of motivations for this:
- genbackend.py was somewhat messy, and difficult to change with the
lack of types. The mobile clients used it as a base for their generation,
so improving it will make life easier for them too, once they're ported.
- It will make it easier to write a .ts generator in the future
- We currently implement a bunch of helper methods on protobuf types
which don't allow us to compile the protobuf types until we compile
the Anki crate. If we change this in the future, we will be able to
do more of the compilation up-front.
We no longer need to record the services in the proto file, as we can
extract the service order from the compiled protos. Support for map types
has also been added.
