Cleans up backpack prototypes/rsis (#2002)

* Backpack rsis up to snuff

* Readds holding meta.json

* Updated bag of holdings license

* Backpacks prototype now clean

Resources/Prototypes/Entities/Clothing/Back/backpacks.yml

@@ -6,17 +6,16 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/backpack.rsi
-    state: backpack
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/backpack.rsi
-    state: backpack
+    state: icon
   - type: Clothing
     size: 9999
     QuickEquip: false
     Slots:
     - back
     sprite: Clothing/Back/Backpacks/backpack.rsi
-    HeldPrefix: backpack
   - type: Storage
     capacity: 100
 
@@ -28,13 +27,12 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/clown.rsi
-    state: clown
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/clown.rsi
-    state: clown
+    state: icon
   - type: Clothing
     sprite: Clothing/Back/Backpacks/clown.rsi
-    HeldPrefix: clown
 
 - type: entity
   parent: BackpackClothing
@@ -44,13 +42,12 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/security.rsi
-    state: security
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/security.rsi
-    state: security
+    state: icon
   - type: Clothing
     sprite: Clothing/Back/Backpacks/security.rsi
-    HeldPrefix: security
 
 - type: entity
   parent: BackpackClothing
@@ -60,13 +57,12 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/engineering.rsi
-    state: engineering
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/engineering.rsi
-    state: engineering
+    state: icon
   - type: Clothing
     sprite: Clothing/Back/Backpacks/engineering.rsi
-    HeldPrefix: engineering
 
 - type: entity
   parent: BackpackClothing
@@ -76,13 +72,12 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/medical.rsi
-    state: medical
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/medical.rsi
-    state: medical
+    state: icon
   - type: Clothing
     sprite: Clothing/Back/Backpacks/medical.rsi
-    HeldPrefix: medical
 
 - type: entity
   parent: BackpackClothing
@@ -92,13 +87,12 @@
   components:
   - type: Sprite
     sprite: Clothing/Back/Backpacks/captain.rsi
-    state: captain
+    state: icon
   - type: Icon
     sprite: Clothing/Back/Backpacks/captain.rsi
-    state: captain
+    state: icon
   - type: Clothing
     sprite: Clothing/Back/Backpacks/captain.rsi
-    HeldPrefix: captain
 
 # Inhands/On mob aren't working until I refactor this file -Swept