#### Problem
Currently, the creation of ShredStorageType::RocksFifo is hard coded in validator/src/main.rs.
But this common code will also need to be used in other places like ledger-tool.
#### Summary of Changes
This PR creates a helper functionShredStorageType::rocks_fifo that takes a total shred_storage_size
and equally allocates to data-shred and coding-shred storage.
#### Problem
When FIFO compaction is used, the size ratio between data shred and coding
shred is set to 1:1 based on the `--rocksdb_fifo_shred_storage_size` arg.
However, BlockstoreRocksFifoOptions::default() uses a slightly optimized
5:4 ratio instead, and the default() function is only used in benchmarks.
#### Summary of Changes
This PR makes both validator argument and BlockstoreRocksFifoOptions::default()
to use 1:1 ratio between data and coding shred size.
#### Problem
blockstore_db.rs has a mutual dependency between blockstore_metrics.rs.
#### Summary of Changes
This PR removes the mutual dependency by moving the option-related stuff
out from blockstore_db.rs to its new home --- blockstore_options.rs.
By doing this, we address the mutual dependency and also make the code cleaner.
Yueh-Hsuan Chiang