move sample code into own file

InvenTree/plugins/action/action.py

@@ -68,25 +68,3 @@ class ActionPlugin(plugin.InvenTreePlugin):
             "result": self.get_result(),
             "info": self.get_info(),
         }
-
-
-class SimpleActionPlugin(ActionPlugin):
-    """
-    An EXTREMELY simple action plugin which demonstrates
-    the capability of the ActionPlugin class
-    """
-
-    PLUGIN_NAME = "SimpleActionPlugin"
-    ACTION_NAME = "simple"
-
-    def perform_action(self):
-        print("Action plugin in action!")
-
-    def get_info(self):
-        return {
-            "user": self.user.username,
-            "hello": "world",
-        }
-
-    def get_result(self):
-        return True

InvenTree/plugins/action/simpleactionplugin.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from plugins.action.action import ActionPlugin
+
+
+class SimpleActionPlugin(ActionPlugin):
+    """
+    An EXTREMELY simple action plugin which demonstrates
+    the capability of the ActionPlugin class
+    """
+
+    PLUGIN_NAME = "SimpleActionPlugin"
+    ACTION_NAME = "simple"
+
+    def perform_action(self):
+        print("Action plugin in action!")
+
+    def get_info(self):
+        return {
+            "user": self.user.username,
+            "hello": "world",
+        }
+
+    def get_result(self):
+        return True