There's no need to populate and use the form fields when we're
reusing a reference. The group and content are already stored
in the model and we can insert more directly.
I found that it's also not needed to update the internal item
because we're not changing the content or group. The same is done
in Citoid when reusing a reference.
Bug: T369003
Change-Id: I57315aafb73b0cd68a0d397d2f79833ac54a7c7f
Mainly leaving out the event handling for the change detection to
still keep it simple.
Also the data flow back for editing the content is still somewhat
opaque because the relevant data is passed by reference. I might
change that in follow up patches so it's more clear.
Bug: T369005
Change-Id: I93b62791ef10bf318697905af8a0c5b5d438fdb5
First step to move the UI parts that are relevant for creating,
editing (and extending) a reference to it's own class.
There remains some duplication because of the sub-referencing in
Citoid currently depending on the static properties to build its
own editing interface.
More patches follow, I just wanted to keep it small for reviewers.
Bug: T369005
Change-Id: I8588cde1a54cd505a57a36ed97fc591653c9fb6f