Initial mockup of the Reptilian species (#6973)

Co-authored-by: ZeroDayDaemon <60460608+ZeroDayDaemon@users.noreply.github.com>

Content.Shared/Body/Part/BodyPartType.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using Content.Shared.Body.Components;
 using Robust.Shared.Serialization;
 
@@ -16,6 +16,7 @@ namespace Content.Shared.Body.Part
         Arm,
         Hand,
         Leg,
-        Foot
+        Foot,
+        Tail
     }
 }