Merge pull request #843 in CASA/casa from feature/CAS-12083 to master
* commit 'f65ccb480217ebca8b09badda965e79763f686de':
remove polaverage from mstransform and add intent and minor updates for sdpolaverage
add a new SD task sdpolaverage
add unit tests for polaverage.
add polaverage to mstransform.