Implement internationalization (i18n) support

[Octobersama]

Implement internationalization (i18n) support
Added translation keys and zh_cn language file

[ceeden]

Thanks for the PR but we have plans to rewrite the config system and redo the GUI, once that gets done translations will be added. I have a long list of translation templates generated, I will add yours to the list.

[Octobersama]

Thanks for the update. I completely understand the plan for the rewrite.
I'm glad to hear that the translated text will be useful for the future version. Please feel free to close this PR whenever you are ready.
Also, if possible, I would appreciate it if you could add me as a co-author in the commit where the translations are eventually added. Here is my info:
Co-authored-by: Octobersama [email protected]
Thank you very much!