Merge behaviors of user/channel types and add support for forHandle

[benoit74]

Fix #338 (and make life easier for everyone)

Rationale:

• it is cumbersome for the end-user to try both channel and user types, there is no way to know in advance which one is correct
• it is easy to programmatically test both parameters one after the other one, there is probably no conflict possible
• since early 2024, Youtube API supports a new forHandle parameter which is probably the one we always want to use (but we have recipes which might still be configured by technical ID, so let's keep previous criteria as a fallback)
• I do not want to wait for a major release to drop --type user so for now I left it as accepted but merge behavior, and a warning is displayed about the fact that this is a deprecated value

[codecov]

Codecov Report

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

Project coverage is 1.51%. Comparing base (dfcf7ae) to head (b138fff).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
scraper/src/youtube2zim/youtube.py	0.00%	15 Missing ⚠️
scraper/src/youtube2zim/scraper.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main    #339      +/-   ##
========================================
- Coverage   1.52%   1.51%   -0.01%     
========================================
  Files         11      11              
  Lines       1118    1119       +1     
  Branches     168     170       +2     
========================================
  Hits          17      17              
- Misses      1101    1102       +1     

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[rgaudin]

👍