Port choices in request widgets to GtkDropDown
Review Request #2290 — Created Feb. 26, 2023 and submitted
This also fixes the actual response as well.
Unlike before, the choice field no longer differentiates between "many" choices/compact choices vs "few", and just always uses a drop down.
Opened a choice request, as well as a request field with a choice in it. Confirmed that selected choices were returned from the dialog.