Export/CDN option to upload "last reviewed versions"

[vlada-dudr]

1. Problem

When a reviewed translation gets edited in turns back to translated state. Which is good. The bad thing is that if one exports only reviewed translation, there is suddenly missing translation until it is reviewed again. Pair this with automatic cdn publishing and suddenly typo fix turns into temporary "untranslating" the key.

2. Solution

Add an option to export Last reviewed version, so editing translation doesn't break exports/cdn.

3. extras

Maybe have an ui to show last valid text somewhere in translations section.