Fix typos, remaining code qa and typing issues resulting in breaking changes

[benoit74]

Fix #131

It's time for this big overhaul of the codebase, it was too complex to include SVG support without proper typing in the "image" module.

Some remarks:

• I also included the move to use IO[bytes] instead of io.BytesIO when possible since it is more generic
• Regarding remainings N803, I decided it was preferable to stick to tag name and to stdlib getLogger name
• In the same philosophy, there is one remaining FBT001 in creator.config_indexing to match argument orders of the libzim creator
• Regarding video.encoding.reencode, I just fixed to return type since it was way more straightforward, including in term of usage. Returning tuple[bool, subprocess.CompletedProcess[str]] | bool seems preferable for the type checker rather than tuple[bool, subprocess.CompletedProcess[str] | None] (it looks like type checker prefer clearly to have two potentials real types rather than optionals)
• NEW: Revisit creator methods manipulating metadata to accept only str | bytes after conversion (and add new explicit conversion method)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (1eddabc) to head (dc57e64).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #178   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           32        32           
  Lines         1452      1475   +23     
  Branches       251       256    +5     
=========================================
+ Hits          1452      1475   +23     

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[rgaudin]

Thank you!
I only have a few questions and suggestions but it's already OK IMO

[rgaudin]

👍