i18n: Show translation levels for each language in the UI (take 2)

With !59420 (merged) being reverted, due to CI failures, the feature needs to be fixed/re-implemented.

original issue: #328430 (closed)

Original issue description

As a first step 👣 toward #18923, we can make the translation levels hardcoded and manually update them on a cadence.

Proposal

  • In the drop-down, show to the user the % of language translated.
  • Allow for manual updates of the hardcoded translation levels.

Design

Add (x% translated) to each language choice. For example, instead of French - français, display French - français (88% translated).

image

Future iterations