Improve experience configuring OTel Semantic Convention compliant ObservationConvention

[shakuzen]

Please describe the feature request.
#3210 describes the general feature of configuring a convention on an Observation API-based instrumentation, which was delivered as ObservationConvention - see the docs and an example in Spring MVC here. This makes it possible for users to use an arbitrary convention that differs from the convention used by the instrumentation. That makes it possible to configure an ObservationConvention implementation for a specific OpenTelemetry Semantic Convention if a user wants. Someone needs to create and configure that ObservationConvention implementation, though.

Building on the above, this enhancement request is to see how we might be able to make it easier for users to configure implementations of ObservationConvention for specific instrumentations targeting a specific version of the OTel Semantic Conventions. That work might not happen in this repository, but this is a convenient place to track it and discuss.

Rationale
While it is already possible for someone to make and configure an ObservationConvention that uses the OTel Semantic Conventions, it is worth exploring if it can be done in a way so that many people aren't writing similar implementations for the same purpose. Versioning and compatibility is another concern - conventions may change over time and users may want to pick a version of the conventions to target so they are not unexpectedly faced with a breaking change.

Additional context
Related issues: #5286 micrometer-metrics/tracing#929