Draft: add modules of drafttests to the proper Doxygen group

This includes `auxiliary`, `draft_test_objects`, `test_airfoildat`,
`test_creation`, `test_dwg`, `test_dxf`, `test_import`,
`test_import_gui`, `test_import_tools`, `test_modification`,
`test_oca`, `test_pivy`, `test_svg`.

These are added to the `drafttests` Doxygen group
so that the functions and classes contained in each module
are listed appropriately in the automatically generated
documentation.

src/Mod/Draft/drafttests/draft_test_objects.py

@@ -34,10 +34,11 @@ Or load it as a module and use the defined function.
 >>> dt.create_test_file()
 """
 ## @package draft_test_objects
-# \ingroup DRAFT
+# \ingroup drafttests
 # \brief Run this file to create a standard test document for Draft objects.
-# @{
 
+## \addtogroup drafttests
+# @{
 import datetime
 import os