Fixed mediastream when hls uses extra arguments

[NickCis]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

This PR fixes the mediastream extractor for sites that uses access_token or extra arguments in the HLS link.

The fix targets particularly to the iframe link of these two sites (the iframe link has to be extracted using the browser, it'll be the url passed to yt-dlp):

• https://www.tvn.cl/en-vivo
• https://www.mega.cl/senal-en-vivo/

These streams have a geo restriction and can only be accessed from Chile.

I have not made any new test, what would be the recommended way to test these changes?.

Fixes #

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

In order to be accepted and merged into yt-dlp each piece of code must be in public domain or released under Unlicense. Check all of the following options that apply:

• 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?

• 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)

[NickCis]

@seproDev I have applied your suggestions and also the "walrus operator" change that @pukkandan suggested (I didn't know that it existed!, Thanks for the lesson 👏 )

[NickCis]

@seproDev Done!