Translation memory policy

### Describe the problem

Some projects might want to keep only approved translations in the translation memory. The current autoclean translation memory only handles stale translated entries, but does not look beyond.

### Solution brainstorm

Turn the current autoclean setting into more of a policy selection for the translation memory:

- Historical translations (the old default)
- Current translations (current Autoclean translation memory)
- Approved translations (new one)

### Describe alternatives you have considered

_No response_

### Screenshots

_No response_

### Additional context

Is there some additional policy to consider?