Invalidate translations

[magyarosibotond]

Is your feature request related to a problem? Please describe.
When working in teams we often face the problem of notifying translators when the base localization changes. With the current setup when a translation is updated (or changed via import) someone has to go through all the locales and clear the content of the changes terms.
This is not scalable when multiple things change.

Describe the solution you'd like
Introduce a new field to the term column which gets invalidated (valid = false) when a value of a locale is updated (import only?). This validity can be double checked by the translators. The key might be more useful on the translation because each translations might have to be verified one by one.

Describe alternatives you've considered
Check out how PhraseApp does this.

Additional context

• N/A