Add Basic Chinese Input Tool

As the UbuntuMate 20.04 daily built iso is currently structured, even though I log in under the "simplified Chinese" (简体中文) locale, there is no mechanism to input Chinese characters. Also, it can show Chinese web pages, but no Chinese UI. (However, add Mate Chinese UI

I suggest that we simply add fcitx-pinyin and other necessary packages in the official iso. This shouldn't be too difficult to implement. Once this is done, we can help testing it. Thanks!

Chinese support has been dropped from the ISO since 19.10. :upside_down_face:

You can acquire the language support manually after the installation.