[ie/twitter] Fix retweet extraction & remove broken fallback

[bashonly]

When the input URL is for a tweet of a retweeted video, the actual tweet that's being reposted should be extracted instead of the content-less retweet itself. This was being done correctly when passing the legacy_api extractor-arg, but the necessary transformations to the GraphQL response were not being made otherwise.

Since I was already rewriting TwitterIE._extract_status(), I cleaned it up by removing the syndication fallback that is now broken. This will make debugging much simpler.

Finally, in the process of running/updating the tests, I realized the TwitterBroadcast extractor was raising an unexpected AttributeError when a broadcast no longer exists, so I added 2 lines to catch that.

Addresses #7850 (comment)

Template

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Copilot Summary

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Summary

🐦🎥🔄

Improve Twitter extraction and fix bugs. Add support for retweets, handle missing or private broadcasts, and use legacy API as fallback. Update and add tests for yt_dlp/extractor/twitter.py.

Oh we are the coders of the Twitter sea
We extract the tweets and the videos with glee
We handle the retweets and the broadcasts that are gone
And we use the legacy API when we need to carry on

Walkthrough

• Remove unused import of functools (link)
• Add and update test cases for TwitterIE class, testing different scenarios of tweets, retweets, and broadcasts (link, link, link, link, link, link, link)
• Add _GRAPHQL_ENDPOINT property to TwitterIE class, returning the appropriate GraphQL endpoint depending on login status (link)
• Modify _graphql_to_legacy method of TwitterIE class, adding support for extracting retweeted status and user from GraphQL response (link)
• Modify _extract_status method of TwitterIE class, changing the order and logic of API calls, preferring legacy API over GraphQL API if not logged in and legacy_api argument is set, and returning retweeted status if present (link)
• Modify _real_extract method of TwitterIE class, removing redundant extraction of media id from video URL (link)
• Modify _real_extract method of TwitterBroadcastIE class, adding a check for the existence of broadcast in API response, and raising extractor error if missing (link)
• Add comment to _real_extract method of TwitterBroadcastIE class, explaining the purpose of broadcast id extraction (link)

[gamer191]

The fallback actually does work-see the message in Discord