Create UI for adding translation of language labels

@cdrini did an import from Wikidata to add translation to language labels few months ago, and it worked well for almost all languages. Though some didn't get imported
Example (some languages aren't translated in Ukrainian):
I can translate them manually, but there is no UI for this currently. Though, when you press edit on language page, you get redirected to [this](https://openlibrary.org/languages/iri?m=edit) page, which kinda looks like some UI, but it doesn't work