Adds briefcase (#6196)

Co-authored-by: mirrorcult <lunarautomaton6@gmail.com>

Resources/Prototypes/Entities/Objects/Misc/briefcases.yml

@@ -0,0 +1,24 @@
+- type: entity
+  parent: BaseItem
+  abstract: true
+  id: BriefcaseBase
+  description: Useful for carrying items in your hands.
+  components:
+  - type: Item
+    size: 60
+  - type: Storage
+    capacity: 60
+    storageSoundCollection:
+      collection: storageRustle
+
+- type: entity
+  name: brown briefcase
+  parent: BriefcaseBase
+  id: BriefcaseBrown
+  description: A handy briefcase.
+  components:
+  - type: Sprite
+    sprite: Objects/Storage/Briefcases/briefcase_brown.rsi
+    state: icon
+  - type: Item
+    sprite: Objects/Storage/Briefcases/briefcase_brown.rsi