Disease and blob camera mobs can move vertically while a location or host hasn't been chosen yet. Revenants can also freely move vertically. (#64626)

I found out on the icebox map, roughly a week or two ago, that the camera mob couldn't be moved to the other station leveleven before the core was placed. I believe this to be an oversight, which is why this PR has been made.
Sentient diseases also suffer from a similar issue while on the host selection stage, so I'm fixing that too.

EDIT: Someone pointed out that revenants (and other mobs with incorporeal movement) don't ignore turfs and obstacles when moving vertically, so I have added a few lines to living/can_z_move to hopefully fix that.

code/modules/mob/camera/camera.dm

@@ -21,5 +21,23 @@
 /mob/camera/canUseStorage()
 	return FALSE
 
+/mob/camera/up()
+	set name = "Move Upwards"
+	set category = "IC"
+
+	if(zMove(UP, z_move_flags = ZMOVE_FEEDBACK))
+		to_chat(src, span_notice("You move upwards."))
+
+/mob/camera/down()
+	set name = "Move Down"
+	set category = "IC"
+
+	if(zMove(DOWN, z_move_flags = ZMOVE_FEEDBACK))
+		to_chat(src, span_notice("You move down."))
+
+/mob/camera/can_z_move(direction, turf/start, turf/destination, z_move_flags = NONE, mob/living/rider)
+	z_move_flags |= ZMOVE_IGNORE_OBSTACLES  //cameras do not respect these FLOORS you speak so much of
+	return ..()
+
 /mob/camera/emote(act, m_type=1, message = null, intentional = FALSE, force_silence = FALSE)
 	return FALSE