Added template for the use of set_test_scene into the test folder (#565)

Author: kolibril13

tests/template_generate_graphical_units_data.py

@@ -0,0 +1,18 @@
+from manim import *
+from tests.helpers.graphical_units import set_test_scene
+
+# Note: DO NOT COMMIT THIS FILE. The purpose of this template is to produce control data for graphical_units_data. As
+# soon as the test data is produced, please revert all changes you made to this file, so this template file will be
+# still available for others :)
+# More about graphical unit tests: https://github.com/ManimCommunity/manim/wiki/Testing#graphical-unit-test
+
+
+class YourClassHere(Scene):
+    def construct(self):
+        circle = Circle()
+        self.play(Animation(circle))
+
+
+set_test_scene(
+    YourClassHere, "<module_name>"
+)  # <module_name> can be e.g.  "geometry" or "movements"