Add an language option

[bYemma]

Feature request

Summary

Make an option to change the language. Default is now "en".

Why is it needed?

Labels in TinyMCE are not localized.

[matdave]

The overall TinyMCE should respect the manager language now. However we do not have translations created for some of the labels. I've created "starters" here: https://github.com/modxcms/tinymce-rte/tree/main/src/js/Translations