Remove `W3CBaggagePropagator` from `@opentelemetry/core`

[nicohrubec]

SentryPropagator (packages/opentelemetry/src/propagator.ts) extends W3CBaggagePropagator and calls super.inject(...).

Vendoring requires the class plus its baggage helpers (getKeyPairs / serializeKeyPairs / parsePairKeyValue) and constants.

[linear-code]

JS-3048

[nicohrubec]

@andreiborza this seems to only be used by the SentryPropagator, so assigning you for now since you are looking into whether we'll get rid of the propagator

[github-actions]

A PR closing this issue has just been released 🚀

This issue was referenced by PR #22702, which was included in the 11.0.0 release.