Bazel / rules_rust / prost example

10/02/2023

At the time of this writing the documentation for rules_rust isn't quite enough to get a working server. There are a few issues. This is working code. It consolidates a couple examples and includes a few fixes.

• futures-core is required in WORKSPACE and the tonic_runtime rust_library_group as tonic uses it when generating streaming gRPCs.
• This shows where to put everything, making clearer which code goes in WORKSPACE or not.
• It keeps the example proto in its own module to make it clearer what depends on what (and what doesn't)
• Makes it clearer that only one crates_repository is needed, where the docs use different crates_repository names and configurations in different sections.
• An out-of-date patch for protoc-gen-prost is removed
• Deprecated parameters are removed
• Example grpcurl commands are included for each server method type in code/server/src/main.rs

Try:

bazel run //code/server