[truth] Backport extractor from yt-dlp

[palewire]

Please follow the guide below

• You will be asked some questions, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your pull request (like that [x])
• Use Preview tab to see how your pull request will actually look like

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Before submitting a pull request make sure you have:

• [x] Searched the bugtracker for similar pull requests
• [x] Read adding new extractor tutorial
• [x] Read youtube-dl coding conventions and adjusted the code to meet them
• [x] Covered the code with tests (note that PRs without tests will be REJECTED)
• [x] Checked the code with flake8

In order to be accepted and merged into youtube-dl each piece of code must be in public domain or released under Unlicense. Check one of the following options:

• [x] 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?

• [ ] Bug fix
• [ ] Improvement
• [x] New extractor
• [ ] New feature

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Description of your pull request and other information

This patch adds a new extractor for truthsocial.com, the microblogging service founded by former U.S. president Donald Trump. Due to its frequent use by the Trump family and other political actors, this would be a useful addition to the library for journalists and other researchers.

[palewire]

This proposal has been updated to act as a backport from yt-dlp, which has reviewed and accepted it. https://github.com/yt-dlp/yt-dlp/pull/4609