Draft: remove old DraftFillet class, and make it a redirect

Remove the make function that creates the old object,
its corresponding Gui Command, and the old `DraftFillet.Fillet`
proxy class, which now is a redirection to the new `Fillet`
class defined in `draftobjects.fillet`.

Also change the unit test, and the `draft_test_object` script
to run `Draft.make_fillet`.

src/Mod/Draft/draftguitools/gui_fillets.py

@@ -201,4 +201,4 @@ class Fillet(gui_base_original.Creator):
             self.doc.recompute()
 
 
-Gui.addCommand('Draft_Fillet_new', Fillet())
+Gui.addCommand('Draft_Fillet', Fillet())