languages: Sync with D-L

Hey could I get a review @gbernard, @afranke, @danigm.

This was roughly generated by

#!/usr/bin/env python3
import json
from pathlib import Path

contents = Path('languages').read_text()

j = json.loads(contents)

for lang in j:
    print(f"{lang['locale']}={lang['name']}")

for lang in j:
    if plurals := lang['plurals']:
        plurals = plurals.strip(';')
        print(f"{lang['locale']}={plurals};")

where languages is obtained by curl https://l10n.gnome.org/api/v1/languages/

EDIT: I added a script to do this manually in the latest commit.