Improve `file2tab` and `tab2file` in `shards_local` to be compliant with ETS functions

[Carlos Andres Bolaños R.A.]

Current file2tab and tab2file works with a list of files instead of a single filename (as ETS functions).

For tab2file function the idea is generate one file per shard using ets:tab2file/3, and also generate a master file with the given Filename that holds the information about the other shards files in order to be able to recover them later using ets:file2tab/1,2.

For file2tab the idea would be read the master file given by Filename, get the rest of the shards files info and then restore the table (using ets:file2tab/1,2 for each shard).