[extractor/ettutv] Add extractor

[elyse0]

IMPORTANT: PRs without the template will be CLOSED

Description of your pull request and other information

This PR adds an extractor for https://www.ettu.tv which is a page for livestreams and videos of European Table Tennis.

Fixes #6359

[debug] Command-line config: ['https://www.ettu.tv/en-int/playerpage/1573849', '--verbose', '-F']
[debug] Encodings: locale UTF-8, fs utf-8, pref UTF-8, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version stable@2023.03.04 [392389b7d] (source)
[debug] Lazy loading extractors is disabled
[debug] Git HEAD: 3e20f18af
[debug] Python 3.10.7 (CPython x86_64 64bit) - Linux-5.19.0-35-generic-x86_64-with-glibc2.36 (OpenSSL 3.0.5 5 Jul 2022, glibc 2.36)
[debug] exe versions: ffmpeg N-108931-g4dda3b1653-20221104 (setts), ffprobe N-108931-g4dda3b1653-20221104, phantomjs broken, rtmpdump 2.4
[debug] Optional libraries: Cryptodome-3.15.0, certifi-2022.09.24, mutagen-1.46.0, sqlite3-2.6.0, websockets-10.4
[debug] Proxy map: {}
[debug] Loaded 1789 extractors
[EttuTv] Extracting URL: https://www.ettu.tv/en-int/playerpage/1573849
[EttuTv] 1573849: Downloading JSON metadata
[EttuTv] 1573849: Downloading JSON metadata
[EttuTv] 1573849: Downloading m3u8 information
[debug] Formats sorted by: hasvid, ie_pref, lang, quality, res, fps, hdr:12(7), vcodec:vp9.2(10), channels, acodec, filesize, fs_approx, tbr, vbr, abr, asr, proto, vext, aext, hasaud, source, id
[info] Available formats for 1573849:
ID   EXT RESOLUTION FPS │   TBR PROTO │ VCODEC        VBR ACODEC    ABR
───────────────────────────────────────────────────────────────────────
278  mp4 480x270     25 │  278k m3u8  │ avc1.420015  278k mp4a.40.2  0k
696  mp4 640x360     25 │  696k m3u8  │ avc1.42001e  696k mp4a.40.2  0k
978  mp4 640x360     25 │  978k m3u8  │ avc1.4d001e  978k mp4a.40.2  0k
2128 mp4 1280x720    25 │ 2128k m3u8  │ avc1.4d001f 2128k mp4a.40.2  0k
4128 mp4 1920x1080   25 │ 4128k m3u8  │ avc1.4d0028 4128k mp4a.40.2  0k

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)

[mtaki14]

Doesn't seem to work for vods now. Maybe something changed?

E.g. https://www.ettu.tv/en-int/video/kolodziejczyk-maciej-falck-mattias/1631141

[bashonly]

@mtaki14 Can you open a new issue?