[webtoonxyz] add support

[Dragonatorul]

Webtoon.xyz uses the same CDN as mangaread.org (WordPressMadara) so this is pretty much a copy-paste of the mangaread extractor.

However, they are also using cloudflare checks. My local tests return the following error even with cookies extracted from Firefox.

» python3 . --cookies ../../cookies.txt https://www.webtoon.xyz/read/the-world-after-the-end/
[webtoonxyz][warning] Cloudflare challenge
[webtoonxyz][error] HttpError: '403 Forbidden' for 'https://www.webtoon.xyz/read/the-world-after-the-end'

EDIT: It worked after adding the correct user-agent:

» python3 . --cookies ../../cookies.txt --user-agent "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0" https://www.webtoon.xyz/read/the-world-after-the-end/
./gallery-dl/webtoonxyz/The World After The End/c000/The World After The End_c000_001.jpg

[enduser420]

Both this and #5140 can be rewritten using the BaseExtractor to prevent having 3 copies of the same extractor.

[Dragonatorul]

Both this and #5140 can be rewritten using the BaseExtractor to prevent having 3 copies of the same extractor.

I'll have a look tomorrow to see how that's done.

[Dragonatorul]

@enduser420 I'm still looking over how BaseExtractor works.

I have a question though:

Notice how each of these 3 sites have a different path. /manga/ vs /read/ vs /webtoon/

From other implementations of BaseExtractor it seems like the presumption is that all instances are using the same path. I suppose we could have {manga|read|webtoon) in the match regexp, but that doesn't feel right to me. Is that alright though?

[enduser420]

Thats alright.

[Dragonatorul]

Superceded by #5166