feat: system function to detect&remove orphaned blocks of a database

[BohuTANG]

Summary

Scan

List all the object dir of a database prefix:

call fuse_data_scan(`<db-name>`);

This function will do the following:

1. list all the dirs of the database prefix
2. return the 'table' dir status(orphaned/attached) and size

Clean

Remove the orphaned(a prefix not related to a table that is in the metasrv) table dir:

call fuse_data_clean(`<db-name>`);

1. list all the dirs of the database prefix with status
2. remove orphaned status dir and all the files

[BohuTANG]

Welcome to comments, cc @dantengsky

[dantengsky]

list all the dirs of the database prefix with status

let's implement this based on the list API first.

and refine the implementation by using undo logs later. but the impl based on list API should be kept, as the last resort (one tool of the doomsday toolkit)