Pull request #913: CAS-14401 set image brightness unit according to the unit of MS data column
Merge in CASA/casa6 from CAS-14401 to master
* commit '26fe7533fa5c48d4f094f7af9596d1626b74432b':
add one more test case: check if task parameter overrides brightness unit
Add type hint and docstring to test helper function
Add description on unit search order
fixed wrong test name
Add supplementary comment CAS-14401 refactoring, type hints, docstrings, and one more test case CAS-14401 make sure CORRECTED_DATA column takes priority CAS-14401 add unit test to verify brightnessunit CAS-14401 add another keyword name to search for brightness unit
