[OTEL] Add propagator support

[AbhiPrasad]

Add OpenTelemetry propagator implementation to extract and inject sentry-trace and baggage headers.

getsentry/develop#733

Initial implementation: #6095

• Add @opentelemetry/core package feat(otel): Add @opentelemetry/core package #6108
• Add base propagator feat(otel): Add base SentryPropagator class #6109
• Add inject functionality feat(otel): Add inject functionality to SentryPropagator #6114
• Add extract functionality feat(otel): Add extract functionality to SentryPropagator #6115
• Update README for propagator instructions chore(otel): Update README to add SentryPropagator info #6126