[extractor/youtube:tab] Support short renderers in playlists

[coletdjnz]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

Note: YouTube doesn't give continuations yet for shorts view, so will only get 100 videos

Fixes #7424

Template

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• Checked the code with flake8 and ran relevant tests

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Copilot Summary

🤖 Generated by Copilot at f9bc450

Summary

🎞️🧪⚠️

Improve YouTube tab page extraction and testing. Handle shorts playlists, pagination, and hidden videos in yt_dlp/extractor/youtube.py.

Sing, O Muse, of the skillful coder who devised
A way to pluck from YouTube's tab pages the varied prizes
Of shorts and playlists, and who tested his creation well
And warned of hidden videos, like Cerberus at the gates of hell

Walkthrough

• Add support for extracting entries from richGridRenderer in YouTube tab pages (link)
• Add test case for playlist of shorts in yt_dlp/extractor/youtube.py (link)