Fix fallback for locale display names

[wackerow]

Description

• Removes all empty strings from the intl folder (will fallback to English string)
• Improve check inside useLanguagePicker to check if we have an internal translation available or not
  If the output of t() matches the English name or the i18n key, then this string isn't available internally and Intl.DisplayNames used as fallback to display the locale name.

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[pettinarip]

Lgtm! it seems to fix the issue.

However, I'd strongly suggest removing the throw errors we have inside the useEffect, since all of them are going to break the client experience. Instead, we can console.error them.

[wackerow]

Okay... @pettinarip note that without the guard for (!sourceName || !targetName), we end up with the possibility of undefined here for these two items... If you're okay with it, let's get this in and I can look into that separately.

[pettinarip]

@wackerow we should assign something to those vars

if (!sourceName) {
  console.error(...)
  sourceName = ""
}

if (!targetName) {
  console.error(...)
  targetName = ""
}