[ie/TV5Monde] Fix extractor

[alard]

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Description of your pull request and other information

This updates the TV5MondePlusIE extractor for the new URL and HTML structure of tv5monde.com.

Fixes #9118

A few open questions:

1. The new website does not seem to offer subtitles (at least I haven't found a video that uses them), so I have not been able to test if this part of the extractor still works.

2. While the extractor is called TV5 Monde Plus, this fixes the behavior for tv5monde.com, which is a different website.

   In my region, tv5mondeplus.com redirects to tv5monde.com. Via a VPN I was able to access the plus version, which is a different website with a different structure. In the US it requires a subscription. As the page structure is different, I have my doubts that the current version of the extractor worked there. I have removed the tv5mondeplus.com URL from the extractor for now.

   Maybe the TV Monde Plus site needs its own custom extractor and this one should be renamed.

If anyone knows more about the location of the subtitles, or has experience with TV Monde Plus, feel free to comment.

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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What is the purpose of your pull request?

• Fix or improvement to an extractor (Make sure to add/update tests)
• New extractor (Piracy websites will not be accepted)
• Core bug fix/improvement
• New feature (It is strongly recommended to open an issue first)

[alard]

@seproDev Thanks for the review. I made the changes you suggested.

[seproDev]

Sorry, I took so long to get back to you. I was kind of dreading taking another look at the site, as the way they expose their metadata is pretty ugly. I have pushed a rework of the metadata extraction. Please take a look and verify that this makes sense.
I am specifically unsure about the title/series/episode distinction, but this is the best I came up with.