When exporters use layout panels, it was possible for their panel ids to
conflict if more than 1 of the same exporter was configured on the same
collection. The result would be that opening/closing a panel in one
exporter would open/close it for all other exporters of the same type.
This fix changes the layout to avoid the issue entirely by using a list
and only having only one exporter drawn at a time.
A few alternate designs were considered but they would either cause
intrusive changes to each location where a layout panel was used or
would result in tricky disambiguation code inside the UI system itself.
Pull Request: https://projects.blender.org/blender/blender/pulls/121555
d089b5e6ad