Add an inline dropdown on the field in a node in the diagram to change its field type.
This dropdown should only be shown when the field is selected (similar to the crud view).

A user should be able to switch from a `mixed` type, but not to it.

Types:
https://docs.google.com/document/d/1rkFUzIEHTzTHBbZHjEwPFE-f4KA-gQYX6cUPA_wvQS4/edit?tab=t.0#bookmark=id.xgcs0brg2b62 

Designs: https://www.figma.com/design/w51HGIb2PDdyZqyCOMMypr/-PROGRAM-92--Data-Model-Design-Experience?node-id=4030-5358&t=HL4nxoA784rUo2i7-4