Add a 'translation test string' in developer options

[david-allison]

Hello there! I am a translator for the Gothic language on Ankidroid and I wondered if it supports Gothic Unicode to display in the UI. In that case I'll switch the translated strings to gothic unicode

If we had a CrowdIn string which only appears in dev/debug options, we'd be able to allow a translator to self-serve these requests

[BrayanDSO]

An EditTextPreference that can have whatever the user type as summary?

[david-allison]

A user can already type a deck name, which will display in the UI

This would be for end-to-end testing from CrowdIn => AnkiDroid