Add items to the ZIM "on the fly"

[dan-niles]

Close #204 Close #209

Changes in this PR:

• Remove --no-zim CLI argument.
• Add items "on the fly" to the ZIM:
  • Videos and video thumbnails are added to ZIM immediately after they are downloaded.
  • Channel branding of main channel (profile.jpg) is added after creating the favicon using it.
  • Subtitles are added to ZIM immediately after download. Information about language codes are cached so that it can be used later on to generate JSON files for individual videos.
  • Use validate_zimfile_creatable from zimscraperlib to validate if ZIM cannot be created at given location / name.
  • Remove add_files_to_zim method from Youtube2Zim class, since we no longer have to copy the whole build directory into the ZIM.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 115 lines in your changes missing coverage. Please review.

Project coverage is 1.58%. Comparing base (5ae8960) to head (1815f28).

Files	Patch %	Lines
scraper/src/youtube2zim/scraper.py	0.00%	113 Missing :warning:
scraper/src/youtube2zim/schemas.py	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #262 +/- ## ======================================== - Coverage 1.63% 1.58% -0.05% ======================================== Files 11 11 Lines 1040 1070 +30 Branches 156 160 +4 ======================================== Hits 17 17 - Misses 1023 1053 +30 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[benoit74]

Nota: just so that it is clear for our future-self, we removed the --no-zim argument since we are now adding files on-the-fly to the ZIM, so there is no added-value / sense to ask to not create the ZIM.

[benoit74]

Oh and btw, we should remove as well the keep_build_dir / --keep as well, build_dir content is not interesting anymore to be kept.

And the documentation about --tmp-dir argument should be revisited, it is not really accurate anymore.

[dan-niles]

I recommend to move as much as possible every steps before the long download_video_files step. I think that download_authors_branding, add_main_channel_branding_to_zim and add_zimui are good candidates.

I have moved add_main_channel_branding_to_zim and add_zimui to run before the download step in 869b499. However download_authors_branding cannot be moved since it depends on the get_videos_authors_info method running before it.

get_videos_authors_info fetches all the information about the authors of videos and then download_authors_branding downloads the branding for the fetched authors.

[dan-niles]

--keep CLI argument removed in 57f5a5d. I also updated the documentation for --tmp-dir in the same commit.