Translation transformer handler

[victorlazzaroli]

Introduce a hook or extension point that allows modification of the raw translation value before the interpolation phase begins.

Issue: #1555

[CodeAndWeb]

We already have this functionality in form of the translate compiler.
It receives the translations before they are committed to the store.
The point in time is a bit earlier than your proposed hook.

[victorlazzaroli]

I considered using the compiler to flatten the tree structure, but the cost is that it has to process the entire file every time it is loaded.
For this reason, I think it is more efficient and convenient to introduce the hook, especially for large files. 😊