[Feat.Req] Pruning msgs from db

[hopeyen]

Problem statement

While there is an API function to delete messages, we should add an periodic pruning event into the listener radio.

Expectation proposal

Add config

• max_storage the maximum storage of generic messages, prune messages from smallest/earliest message ID until there's at most max_storage message left: [earliest_id..latest_id-max_storage]
• message_pruning_age prune messages of old age: timestamp + pruning_age < current_time

Alternative considerations
Certain message types might have different preference (such as to keep upgrade_intent_message longer than public_poi_message. We may want a configuration matrix, but treat them all the same for now.

Additional context
graphops/graphcast-sdk#268