Which issue(s) does the PR fix:

Implement support for versioned OTel semantic conventions, with automatic querying for all metric versions. Behind feature flag "semconv-versioned-read" - this is a working title, final name is TODO :)

TODO:

• Transform the label names of all series belonging to other versions to correspond to the queried version
• Compute semantic conventions group IDs (how?) - potentially unnecessary with next version of semantic conventions format
• Use OTel schema format v2, where definitions are included (@jsuereth knows)
• Decide on feature flag name
• Resolve TODOs in code

Does this PR introduce a user-facing change?

[FEATURE] Add support for versioned OTel semantic conventions, with automatic querying for all metric versions.