Support setting `if-dependencies` in `from_deps` transforms

[ahal]

We had a use case where we wanted to use from_deps to add if-dependencies, but we needed to create a follow-up transform to add them.

This feels like a reasonable thing for from_deps to handle out of the box.

[ahal]

I think for starters it's fine if it's all or nothing. E.g, either all deps are if-dependencies or none of them are. Maybe eventually we'll want to be able to say some subset of them are and another subset aren't.. but we can cross that bridge when we come to it.