Optimization of the Staging Area should index the data

[osopardo1]

Qbeast Format supports reading files not indexed with the Otree / not containing Qbeast Metadata. We call it the "Staging Area".

To reduce the overhead of writing small files, we use an operation called Compaction on this area. But changes on #284 would reduce the implementation of compaction to a single call to the optimize method. On the other hand, the optimization of the Staging Area should NOT be the same than the optimization for Indexed Files.

The solution proposed is:

1. Delete compact() as an actionable command both in IndexedTable and QbeastTable.
2. Remove CompactTableCommand.
3. Remove or fix tests accordingly.
4. Rename compact() method in the DataWriter interface and implementation. Might be confusing to still use that naming internally.
5. When optimize() is applied to the Staging Area -> index the data.
6. When optimize() is applied to other areas / revisions -> maintain the current implementation.