Handle books location, and update them when adding book to title

[benoit74]

Add support for handling where book is currently stored (when we retrieve the zimfarm notification typically) and when we expect it to be stored (based on current title settings).

[codecov]

Codecov Report

❌ Patch coverage is 96.58120% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.68%. Comparing base (7904d19) to head (41f3c80).
⚠️ Report is 3 commits behind head on cms-upgrade.

Files with missing lines	Patch %	Lines
backend/src/cms_backend/db/book.py	84.61%	1 Missing and 1 partial ⚠️
backend/src/cms_backend/utils/filename.py	95.83%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           cms-upgrade     #123      +/-   ##
===============================================
+ Coverage        84.34%   85.68%   +1.33%     
===============================================
  Files               27       28       +1     
  Lines              805      908     +103     
  Branches            58       76      +18     
===============================================
+ Hits               679      778      +99     
- Misses             113      114       +1     
- Partials            13       16       +3     

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