AI translate update extractor

This change might need a warning that it depends on ai 1.2.x, and including it into custom_field might need to be timed together with the first (stable?) release in that branch...
I don't suppose it would be possible to both support 1.1.x-style FieldTextExtractor plugins, as well as 1.2.x-style...

We can document the module version requirement on the project page but I would prefer we stick with the 1.2 version as the source of truth. Otherwise, someone could make their own patch for 1.1 compatibility if really desired. I don't think there is even enough users that are going to be affected anyhow since ai_translate & custom_field usage together is likely gonna be very low at least for now until more people adopt AI.

Tested this update, and it works well with ✨ Add text extractor plugins for image and link field types Active .

Tested this MR with the newly released 1.2.0-alpha1 release of the AI module, and everything works as expected.