[Meta] Extensions known that don't work

- MyReadingManga (EN) -> `Stub!` Exception on  `android.webkit.WebSettings.getDefaultUserAgent` (might be fixed?)
- Manhuaren/漫画人 (ZH) ->`Stub!` Exception on `android.text.format.DateFormat.format`
- Imperfect Comics -> needs investigation
- Viz -> somehow we need to handle logins
- AllHentai (RU) -> Authorization via WebView is required to view content
