* StoreKVPair protobuf message definition and generated go types
* store WriteListener
* update MultiStore, CacheWrap, CacheWrapper interfaces
* adjust KVStores to fit new CacheWrapper interface
* new ListenKVStore
* adjust multistores to fit new MultiStore interface and enable wrapping returned KVStores with the new ListenKVStore
* typo fixes in adr
* ListenKV Store test
* update server mock KVStore and MultiStore
* multistore unit test; fix multistore constructor
* update changelog
* fix bug identified in CI
* improve codecov, minor fixes/adjustments
* review fixes
* review updates; flip set to delete in KVStorePair, updated proto-docs from running 'make proto-gen'
* ADR-038 state listening
* updates/fixes
* review fixes/adjustments
* review fixes/adjustments part 2
* review updates part 3: refactor after review to coordinate store changes with block and tx messages and enable file pruning
* review updates part 4: additional details and fixes; addressing recent feedback; use binary protobuf encoding for kv pairs in files
* review updates part 5: formatting fixes; updated StreamingService/Hook interface
* auxiliary streaming/queue service
* review updates part 6: update StoreKVPair to differentiate between Set and Deletes on nil byte values; some minor adjustments
* typo fix