Better naming of gRPC-related crates and URIs

[emilk]

What

• A Rerun Data Platform gRPC url now has the rerun:// schema
• The gRPC protobuf types are defined in re_protos
• The builder of the types is called re_protos_builder
• The gRPC client is in re_grpc_client
• The feature-flag is called grpc

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!
• If have noted any breaking changes to the log API in CHANGELOG.md and the migration guide

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

To run all checks from main, comment on the PR with @rerun-bot full-check.

[github-actions]

Deployed docs

Commit	Link
399dcca	https://landing-hoq3bmc11-rerun.vercel.app/docs

[emilk]

After talking to @zehiko, we've decided to further rename re_grpc_types to re_protos