Add ability to select form mode

Problem/Motivation

I worked with custom Form modes for the User entity and I had to configure some dependencies for a custom form mode. I successfully configured them but then (during configs export), I discovered that the fields for which I configured the conditions, became enabled in the default form display. After hiding these fields for the default form state, my conditions disappeared.

Seems like the conditions work for all form states at once and I can't select the specific form state for the usage of the conditions.

Proposed resolution

It would be great to have some selector of form mode(s) or form state(s) where conditions should be applied.