Add provider for OpenTelemetry propagator

[adinauer]

Description

See #2254 (comment)

[adinauer]

There is already a provider (https://github.com/getsentry/sentry-java/blob/main/sentry-opentelemetry/sentry-opentelemetry-agentcustomization/src/main/java/io/sentry/opentelemetry/SentryPropagatorProvider.java) but it's located in the sentry-opentelemetry-agentcustomization. This dependency has to be added as an additional dependency for now. We should do more testing towards using our OpenTelemetry offering without an agent and see if that's all that's needed.

There's likely going to be problems around classloaders when simply adding the contents of the module to e.g. sentry-opentelemetry-core as it's currently loaded into a separate classloader for the agent.