[Proposal] Fork semantic-convention specific build-tools into a semantic-conventions-tools repository

[jsuereth]

Today the build-tools repository is an amalgamation of three major components:

• A docker image with C++ development tooling
• A docker image to validate the open-telemetry/opentelemetry-proto repository
• Tooling for semantic conventions.

Due to the split ownership model, no single group feels responsible and simple fixes like dependabot PRs have lagged in this repository.

I'd like to propose splitting out components with clear ownership. For Semantic Conventions this would be the tooling around schemas + code generation. We would still build a docker image from the new repository, but ownership would be 100% the domain of semantic-conventions maintainers and would now be part of semconv triage.

Related: open-telemetry/opentelemetry-cpp#2550
Related: open-telemetry/opentelemetry-specification#3899

[lmolkova]

I believe it's now done with https://github.com/open-telemetry/weaver. Can we close it?