Do not insert all RSYNC paths in database

[benoit74]

Fix #220

Changes (all for the stage where we insert RSYNC result as Url into database):

• ignore all directory entries
• ignore all entries in an /old/ subfolder
• take into account the book selection which might have been passed
• display statistics after operation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 0.76%. Comparing base (59ebd30) to head (51f47f4).

Files	Patch %	Lines
src/gutenberg2zim/urls.py	0.00%	16 Missing :warning:
src/gutenberg2zim/entrypoint.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #221 +/- ## ======================================== - Coverage 0.76% 0.76% -0.01% ======================================== Files 15 15 Lines 1560 1575 +15 Branches 336 341 +5 ======================================== Hits 12 12 - Misses 1548 1563 +15 ```

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