Note that I changed the language names to lookup from {lang}-{region} instead of
just {lang}, because Genshin Impact supports both zh-cn and zh-tw locales.
zh-tw's tranlsation is different zh-cn.
This commit adds the translation and registers the language in the code,
so that french translations show up in the launcher.
This translation, though not perfect should be understandable to most
French speakers :) If you have any comments or suggestion, feel free to
leave them here!
