Make `MongoHandlerContext` public to leverage contextual information to customize `Observation`s

[kevinat]

Observation tracing remote service name is hardcoded as "mongo". For microservices, we may need remote service name in pattern mongo-dbname.

MongoObservationCommandListener.java

line 108:
--- observationContext.setRemoteServiceName("mongo");
+++ observationContext.setRemoteServiceName("mongo-%s".formatted(databaseName));

[mp911de]

We could introduce template method hooks to customize the context and the observation so you can customize both, the context and the Observation. Paging @marcingrzejszczak and @jonatan-ivanov for guidance.

[marcingrzejszczak]

One can already do that via the ObservationFilter mechanism

[mp911de]

Thanks a lot. I'm going to make our MongoHandlerContext public to provide access to underlying details.