[Entity] Add Ian's Backpack (#15519)

* Initial commit

Add Ian's backpack

* Fixed inhand sprites

* Add fill to HoP Locker

Added Ian's 50% probability chance to spawn Ian's backpack in HoP locker

Resources/Textures/Clothing/Back/Backpacks/ian.rsi/meta.json

@@ -0,0 +1,26 @@
+{
+    "version": 1,
+    "license": "CC-BY-SA-3.0",
+    "copyright": "Made by RobbyTheFish(github) for ss14.",
+    "size": {
+        "x": 32,
+        "y": 32
+    },
+    "states": [
+        {
+            "name": "icon"
+        },
+        {
+            "name": "equipped-BACKPACK",
+            "directions": 4
+        },
+        {
+            "name": "inhand-left",
+            "directions": 4
+        },
+        {
+            "name": "inhand-right",
+            "directions": 4
+        }
+    ]
+}