fixes ghosts not having a collidable component and adds a ghost collision flag (#1675)

Co-authored-by: ancientpower <ancientpowerer@gmail.com>

Content.Shared/Physics/CollisionGroup.cs

@@ -20,6 +20,7 @@ namespace Content.Shared.Physics
 		VaultImpassable = 1 <<  3, // 8 Things that cannot be jumped over, not half walls or tables
 		SmallImpassable = 1 <<  4, // 16 Things a smaller object - a cat, a crab - can't go through - a wall, but not a computer terminal or a table
         Clickable       = 1 <<  5, // 32 Temporary "dummy" layer to ensure that objects can still be clicked even if they don't collide with anything (you can't interact with objects that have no layer, including items)
+        GhostImpassable = 1 <<  6, // 64 Things impassible by ghosts/observers, ie blessed tiles or forcefields
 
         MapGrid         = MapGridHelpers.CollisionGroup, // Map grids, like shuttles. This is the actual grid itself, not the walls or other entities connected to the grid.
 

Resources/Prototypes/Entities/Mobs/Player/observer.yml

@@ -7,6 +7,12 @@
   - type: Mind
   - type: Physics
     mass: 5
+  - type: Collidable
+    shapes:
+    - !type:PhysShapeAabb
+      bounds: "-0.35,-0.35,0.35,0.35"
+      mask:
+      - GhostImpassable
   - type: Eye
     zoom: 0.5, 0.5
     drawFov: false