[extractor/youtube] Extract title in YouTube Music search results

[kangalio]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

This PR extracts the video title of YouTube Music search results and returns them as a new title field in the output.

Fixes #7095

Template

Before submitting a pull request make sure you have:

• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests
  • I checked flake8 but didn't manage to run the tests. python test/test_download.py TestDownload.youtube said TestDownload has no such attribute; neither when replacing youtube with YouTube, YouTubeIE, or Youtube

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• I am the original author of this code and I am willing to release it under Unlicense
• I am not the original author of this code but it is in public domain or released under Unlicense (provide reliable evidence)

What is the purpose of your pull request?

• Fix or improvement to an extractor (Make sure to add/update tests)
  • I did not update tests because I was unsure how. Grepping for musicResponsiveListItemRenderer didn't turn up anything so at first I assumed that entire renderer extractor was untested, but while writing I realize the tests query the YouTube API in real-time? Looking at YoutubeMusicSearchURLIE._TESTS, is url the URL to be queried and info_dict the expected extracted value?
• New extractor (Piracy websites will not be accepted)
• Core bug fix/improvement
• New feature (It is strongly recommended to open an issue first)

Copilot Summary

🤖 Generated by Copilot at 73830e1

Summary

🎵🛠️🏷️

Add video titles to YouTube Music tab urls. Fix missing titles for some music videos by extracting them from the renderer object in yt_dlp/extractor/youtube.py.

_music_responsive_list_entry
Adds video title to url
Fixing a bug in autumn

Walkthrough

• Add video title to url result in YouTube Music tab extractor (link)

[pukkandan]

• _Looking at YoutubeMusicSearchURLIE._TESTS, is url the URL to be queried and info_dict the expected extracted value?

Yes, but we have no mechanism to test the intermediate url_result. So don't worry about it.