feat: Add RPG cog with character and inventory features

Sets up RPG system as a Redbot cog with core mechanics
Implements character creation, class selection, and stat management
Adds action commands for attacking and healing
Provides inventory and shop functionality for item management
Introduces interactive UI menus for user engagement

rpg/info.json

@@ -0,0 +1,11 @@
+{
+    "author" : ["UnstableKitsune (unstablekitsune)"],
+    "install _msg" : "Oh you installed me! How dare you obtain me! return me right now!",
+    "name" : "RPG",
+    "short" : "Its a TTRPG",
+    "requirements" : [""],
+    "permissions" : [""],
+    "tags" : [""],
+    "min_python_version" : [3, 1, 1],
+    "end_user_data_statement" : ""
+}