Upload translations to all strings in a project

### Usecase

- I get an old file that had nice translated strings on it, but the project has moved it to several files now.
- I want to see if can improve my translations, but I am not sure
- I feed the file to weblate and weblate tells me it could be used to translate some untranslated strings, and others that have been translated by us already
- I can review them before they get saved as my suggestions or translations, and if I discard them, they will not affect the database