[extractor/Facebook] fix: Add dash-manifest URL to formats

[ringus1]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

Adds dash-manifest-url to formats if accessible.

Fixes #7742

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

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• Fix or improvement to an extractor (Make sure to add/update tests)
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• Core bug fix/improvement
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Copilot Summary

🤖 Generated by Copilot at 8b88bcd

Summary

🛠️🎞️🔗

Fix DASH extraction for some Facebook videos by passing mpd_url to _parse_mpd_formats in facebook.py

mpd_url added
To resolve relative paths
Winter of DASH woes

Walkthrough

• Pass mpd_url parameter to _parse_mpd_formats to resolve relative URLs in MPD manifest (link)