feat: add full proto name to generated structs

[tl-helge-hoff]

Big refactoring of how to use grpc-build. There's now a builder pattern to set up the tonic/prost configuration, and the building is more manual compared to relying only on tonic as we did before

Also:

• Added grpc-build-derive to hold the proc-macro generating NamedMessage
• Added grpc-build-core
• put grpc-build in its own lib.
• remove Cargo.lock

e.g:

// Under the package test.helloworld.
Struct MyMessage {
  my_field String;
}
// We now add an impl:
impl NamedMessage for MyMessage {
    const NAME: &'static str = "test.helloworld.MyMessage";
}

[conradludgate]

Seems ok, I'm gonna need to test it a bit more to be fully happy with it

[conradludgate]

Ok, this is currently a breaking change (even if it doesn't seem like one).

Most users have grpc-build as part of their build-dependencies, but after the code is generated, it still relies on the macros to exist in the normal dependencies. Requiring users to have grpc-build-derive in their regular depedencies.

[conradludgate]

Also, our personal use of grpc-build makes use of the type_attribute feature to add serde support to our messages. Turns out that prost-build uses a hashmap internally for attribute support so it's strictly overriding.

I'll think about this more to hopefully find a solution

[conradludgate]

Currently this is still a breaking change (going from FnOnce to Fn). Not sure what I want to do about that. Cloning and reusing the pre-made config results in annotations being added on the impl which is wrong.

I tried just implementing all of them in mod.rs but that results in

impl google::protobuf::Empty {
    fn ... {}
}

which doesn't work (prost by default won't build those in).