French language file 404

[c4ntin]

If you define the language option with "fr_FR" or "fr", tinymce try to retrieve "https://cdn.tiny.cloud/1/xxxxxxxx/tinymce/5.6.2-104/langs/fr.js" that doesn't exist but the file fr_FR.js stills present.

I think the bug was introduce by the lastest fixes: 5429, 285 and you forget to rename the file.

[c4ntin]

we forget to do the fr => fr_fr in one page..... the bug 5429 should be solve to avoid this kind of mistake...