Replace all 'Twitter' links with 'X'

[alisina97]

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:

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

• I am the original author of this code and I am willing to release it under Unlicense

What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

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Description of your pull request and other information

Replaced all "Twitter" links in the codebase and documentation with their "X" equivalents to align with the platform's rebranding. Only the links were updated, as other occurrences of "Twitter" in the code or filenames were left unchanged to avoid potential issues.

• Updated documentation and comments containing links to "Twitter."
• Verified all updated links function correctly without breaking existing workflows.

This change ensures the repository is consistent with the platform's new branding while maintaining stability for all other aspects of the project.

[dirkf]

Does this make the extractor functional for X.com? See #32968 (comment) and linked issue.