[ie/eggs] Add extractors

[subsense]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

This PR adds support for extracting audio from the music platform Eggs.

For a single page, it extracts one audio file.
For an artist page, it downloads all audio files from the list.

• Single Page : https://eggs.mu/artist/32_sunny_girl/song/0e95fd1d-4d61-4d5b-8b18-6092c551da90
• Artist Page : https://eggs.mu/artist/32_sunny_girl

It didn't seem like there were any basic JSON or API endpoints available on the site.
I'm still a beginner, so please go easy on me.

Fixes #11843

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

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)

[seproDev]

Having a quick look at the app, there exists a JSON API
Some of the useful endpoints are:

https://app-front-api.eggs.mu/v1/musics/[song_id]
https://app-front-api.eggs.mu/v1/playlists/[playlist_id]
https://app-front-api.eggs.mu/v1/artists/[artist_slug]

Headers are

Accept: */*
apVersion: 8.2.00
Authorization: Bearer
deviceId: 9bbb0e747d45c5f4
deviceName: Android
User-Agent: flamingo/8.2.00 (Android; 14)

deviceId should be a random 16 character hex code.

I, personally, would vastly prefer using the api instead of relying on regexing the webpage.

[subsense]

Ah, I hadn’t looked into the Android app. Thank you for the hint.

It seems that for retrieving the API, in addition to at least the deviceId, also need the apVersion and deviceName. Is it okay to omit specifying anything beyond those?

Also, it appears that on an artist’s page or a single’s page, some tracks may be YouTube links.
Example URL:
https://eggs.mu/artist/KAMO_3pband/song/1d4bc45f-1af6-47a9-8b30-a70cae350b4f
https://eggs.mu/artist/KAMO_3pband

In that case, I think the appropriate approach would be to call an existing YouTubeIE or similar to handle the processing. If so, is there a way to save the output in m4a or mp3 formats? requested_formats?

[seproDev]

Is it okay to omit specifying anything beyond those?

imo. that's fine. Mabe include the Accept: */* part.

If so, is there a way to save the output in m4a or mp3 formats? requested_formats?

Not from the extractor side. The extractor should just return a url result to YoutubeIE. The user can then use -x to download just the audio.

[seproDev]

I've reworked the extractors a bit