Migrate all codegen to weaver

[jsuereth]

• [x] Document how to do codgen (see https://github.com/open-telemetry/weaver/blob/main/crates/weaver_forge/README.md)
• [X] We want a mechanism to not force folks to write JQ (see #246, release v0.7.0)
• [ ] Migrate Python (@lmolkova)
• [ ] Migrate Java (@jsuereth)
• [ ] Migrate Go (@trisch-me)
• [ ] Migrate Typescript (@MSNev)
• [ ] Migrate Rust (@lquerel)
• [ ] Migrate .NET (@joaopgrassi)
• [ ] Migrate C++
• [ ] Migrate PHP
• [ ] TODO - check with other SiGs
• [ ] Collector metadatagen? (@jsuereth)

[joaopgrassi]

For reference, .NET semconv "package" is here: https://github.com/open-telemetry/opentelemetry-dotnet-contrib/tree/main/src/OpenTelemetry.SemanticConventions

[trisch-me]

for the golang - https://github.com/open-telemetry/opentelemetry-go-build-tools/tree/main/semconvgen