Add xenos (#1204)

* Add xenos for stress test

Pretty hacky and not how I'd do it long-term

* Remove claws

* Add in unarmed combat behaviors

* Cleanuppppp

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Resources/Textures/Mob/xeno.rsi/meta.json

@@ -0,0 +1,19 @@
+{
+    "version": 1,
+    "size": {
+        "x": 64,
+        "y": 32
+    },
+    "license": "CC-BY-SA-3.0",
+    "copyright": "https://github.com/discordia-space/CEV-Eris/raw/7344da18b5e3dd0b1994a84e9c9c0774d71b93a5/icons/mob/alien.dmi",
+    "states": [
+        {
+            "name": "running",
+            "directions": 4
+        },
+        {
+            "name": "standing",
+            "directions": 4
+        }
+    ]
+}