[Usage Collection] Collect Feature Usage

[afharo]

In #60984 we added an API to keep track of the usage of features. We should create a usage collector to report that info in the telemetry payloads.

N.B.: The data returned by the existing APIs is kept in-memory. Server restarts might affect the results. We might want to consider persisting the telemetry-to-be data in a saved object if necessary.

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[pgayvallet]

The data returned by the existing APIs is kept in-memory. Server restarts might affect the results. We might want to consider persisting the telemetry-to-be data in a saved object if necessary

Yea, for the initial version of the feature, using only memory storage was considered acceptable due to the fact that only the time of the last usage of the licensed features is used. If we need to aggregate stats around that, using a more persistent storage will probably be necessary.

[afharo]

I recall @kobelb had some thoughts around that. I think he suggested to persist it only for telemetry purposes, leaving the current behaviour for external users unchanged. But I may have misunderstood :)

[afharo]

I think that we may be able to implement this in a fairly easy way once we've got the Server Counters @Bamieh is working on :)

[Bamieh]

Adding . to follow up once the server counters feature is merged :)