Add GetMultipleChannels method that complements SetMultipleChannels #32
Description
In the method, SetMultipleChannels exists as a member of the VeriStandTestCase class for convenience. A complementary version called GetMultipleChannels would be helpful for running tests.
Right now, the method is to get the WorkspaceManager reference using a property node, then utilitze the VeriStand API to read multiple channels.