Make FIFO validator arguments public

[yhchiang-sol]

Summary of Changes

Make two FIFO validator arguments public: --rocksdb-shred-compaction and --rocksdb_fifo_shred_storage_size.

When --rocksdb_fifo_shred_storage_size is unspecified, it is now derived from --limit-ledger-size by assuming each shred takes 3200 bytes where data + coding shreds contribute 50% of the data size.

So with the default --limit-ledger-size (200,000,000), we will allocate around 300GB to data + coding shreds.