Fix remaining code qa and typing issues resulting in breaking changes

[benoit74]

https://github.com/openzim/python-scraperlib/pull/128 has shown that there is some code qa / typing issues that have to be fixed but will ultimately lead to a breaking change in term of API, hence needing a major release.

• fix all FBT001 / FTB002
• fix N813, N818
• rename getLogger to get_logger
• decide about N803 issues in config_metadata of zim/creator.py (this has been made intentionally to match the real tag name)
• fix many typing issues:
  • the ones associated with RUF013
  • the ones around metadata validation
  • other issues should be investigated as well

[benoit74]

We should as well rename image/convertion.py to image/conversion.py

[benoit74]

Fix reencode return type to be consistent + add type hints (code is ready in fix_reencode_return_types branch but it is a breaking change in term of API).