migrate_database_lmdb_to_rocksdb improvements

[RickiNano]

The migrate_database_lmdb_to_rocksdb option is running for a very long time with the current ledger size (almost 200 million blocks). On my local machine it took 65 minutes to complete. Nothing is written on screen during this process and users may think the process has stalled. This PR adds some progress feedback. One update for each of the 7 tables that are migrated. It also adds a simple disk space check to warn users if they might not have enough space to complete the migration. ~~The current converted RocksDb database is 73 GB, and the warning is given if the system has less than 75GB available.~~ The warning is given based on the size of the LMDB database that is being migrated. The final RocksDb size is approximately 65% of the LMDB space.