Respect loaded mask cube properly in spectral extraction. (#3319)

* Track loaded mask cube in cubeviz

* First pass at handling mask cube in extraction

* Fix type

* Add changelog

* Handle mask cubes that have NaNs instead of 0s

* Act on copy of this mask array

* Don't save DQ array as loaded_mask for JWST

* Add snackbar warning and note in docs

* codestyle

* Add extraction test on file with mask

* Codestyle

(cherry picked from commit bf8cb26)

jdaviz/configs/cubeviz/plugins/tests/test_parsers.py

@@ -222,7 +222,7 @@ def test_manga_cube(cubeviz_helper):
     se.function = "Mean"
     se.extract()
     extracted_max = cubeviz_helper.get_data("Spectrum (mean)").max()
-    assert_allclose(extracted_max.value, 2.836957E-18, rtol=1E-5)
+    assert_allclose(extracted_max.value, 2.836957E-18)
     assert extracted_max.unit == u.Unit("erg / Angstrom s cm**2 pix**2")