Add a Feature Type for the emergency=assembly_point tag

[CoderThomasB]

Description

Currently the emergency=assembly_point is not accessible from the Feature Type selection menu meaning that the emergency=assembly_point has to be added manually; this makes mapping of assembly point much harder. It would be nice to have an "Emergency Assembly Point" type listed in that menu.

https://wiki.openstreetmap.org/wiki/Tag%3Aemergency%3Dassembly_point