remove 4channel-specific site code, fixes #1448 (broken captcha for sfw 4chan boards)

[Twinov]

Captcha for sfw 4chan boards broke because 4chan stopped using the 4channel.org domain.
This PR removes the code for 4channel.org, and after testing can pass the Cloudflare check and captcha again (deleted cookies and then tried getting a captcha and posting).

[ultra-taco]

Post a universal APK please

[ultra-taco]

I went ahead and just built it myself (commit aeaafbcbb5216ba411b0ec871fa71dc83c06e676)

EDIT 3: Universal APK here. This is an actual release build (performance improvement) https://mega.nz/file/XCJVzbaJ#fkhJUiyGJ56xqtcY1d6y-z0XulaTn4ndmACgOG_F-CM

4ch pass users: everything just works captcha solvers: you may need to open up the 'report post' window to complete a cloudflare captcha, then after that posting will function as normal

[NagoorBabuSir]

I went ahead and just built it myself (commit aeaafbc)

EDIT: Universal APK here https://mega.nz/file/LGghFC5a#_6PmnOxqi2J8ZynCD18kE9Lu5dvZpeWL50IP77_0V1o

Thank you sir

[Twinov]

looks like theres a new reason it's broken, captcha json is in a new format with some pcd stuff that breaks the existing parser (and probably needs some new waiting logic idk) tbh I don't really have interest in fixing anything related to the captcha and I'll probably just start using a Pass but I think anyone who's interested can look into this KurobaEx commit and go from there https://github.com/K1rakishou/Kuroba-Experimental/commit/271bd104eb1c3be2bfcca76949e65de6f73f6a50