perf(su): implement SU datastore to run purely on rocksdb

[VinceJuliano]

Background

Under heavy load, the SU database implementation on postgres runs into performance issues. When there are a lot of writes going on the writes become very slow etc... RocksDB was added originally because on the message list query because it contains json data which was stored in postgres, was very slow for large amounts of data.

Solution

To solve this, we can add another RocksDB directory into the SU that will hold the index information. Then we can remove postgres.

1. implement a new Data Store that runs only on RocksDB. 1 Rocks database for the binary data which already exists for the messages and runs in Blob mode for large data, and another Rocks directory that holds the index information and runs in the regular mode.

2. Write another binary like the migration binary to migrate the index information. This should be much faster then the one that migrates the Message bundles themselves because it only needs to grab index info which is quicker to fetch from postgres.