badger side cache and garbage collection

[mleku]

the storage of events on the badger side should remain less than the IC but for reasons of efficiency in both time and cost of access to the IC the badger event store needs to have cache management strategies to contain the age and size of the database, as well as to immediately store everything in parallel with the IC - IC's main purpose is propagating events to multiple relays

[mleku]

tasks:

• [x] created configuration parameters for GC
• [x] add access table for events
• [x] implement cache operation modes - purge vs overflow
• [x] implement GC run logic
  • [x] firehose testing tool that blasts events and pulls them with a bias towards previously requested

[mleku]

testing tool actually implemented as tests

all tasks complete, closing issue