Add test to verify that specifying standard qtables and a quality is equivalent to specifying only a quality

Author: Kyliroco

Tests/test_file_jpeg.py

@@ -614,6 +614,10 @@ def _n_qtables_helper(n: int, test_file: str) -> None:
                     None
                 )
             ]
+            
+            qtable_from_qtable_quality = self.roundtrip(im, qtables={0:standard_l_qtable,1:standard_chrominance_qtable}, quality=75).quantization
+            qtable_from_quality = self.roundtrip(im, quality=75).quantization
+            assert qtable_from_qtable_quality == qtable_from_quality
             # list of qtable lists
             assert_image_similar(
                 im,