Multi-process reads for RocksDB among multiple Faust apps

[wbarnha]

I'd like to be able to setup multiple workers/Faust Apps that have the same name to read the same Faust Table entries. I may need to make some changes to python-rocksdb in order to achieve this.

I understand some of this functionality was added in #98, the note from Ask Solem in robinhood/faust#299 (comment) is no longer true.

Taken from https://github.com/aayushKumarJarvis/rocks-wiki/blob/master/RocksDB-FAQ.md:

Q: Can I write to RocksDB using multiple processes?

A: No. However, it can be opened in read-only mode from multiple processes.

Q: Does RocksDB support multi-process read access?

A: RocksDB support multi-process read only process without writing the database. This can be done by opening the database with DB::OpenForReadOnly() call

Could we have a Faust app configured to only read from a RocksDB file so that multiple processes could share one RocksDB file and only one process writes to the RocksDB file?