Adds the Odyssey gamemode. (#18972)

https://forums.aurorastation.org/topic/20198-mission-briefing-auroras-gamemode-revolution

To-do:

- [x] Finish storyteller verbs.
- [x] Storyteller landmarks.
- [x] Proper storyteller spawning. Right now the gamemode system is
happy with just picking one storyteller and no actors.
- [x] Antagonist whitelists code.
- [x] Adding the Storyteller whitelist.
- [x] Mission map loading code.
- [x] Map in a bunch of missions.
- [ ] Storyteller adminhelps.

---------

Co-authored-by: Matt Atlas <liermattia@gmail.com>
Co-authored-by: DreamySkrell <>

code/modules/admin/buildmode/click_handler.dm

@@ -13,6 +13,9 @@
 	build_modes = list()
 	for(var/mode_type in subtypesof(/datum/build_mode))
 		var/datum/build_mode/build_mode = new mode_type(src)
+		if(build_mode.permission_requirement)
+			if(!check_rights(build_mode.permission_requirement, FALSE, user))
+				continue
 		build_modes += build_mode
 		if(build_mode.the_default)
 			current_build_mode = build_mode