Workspace Software Upgrade Channel API

User Story: As a fleet management engineer I need to be able to change the software upgrade channel thought he developer API against a select set of devices for wider fleet testing.

AC:

Have an API to set the on developer.webex.com to set the software upgrade channel of a workspace.

Specific need: Before deploying firmware to the entire fleet, we choose devices within different regions and network fabrics to deploy firmware updates to for limited testing prior to a fleet wide migration. Currently, we are only able to do this one device at a time through Control Hub taking significantly longer than the CLI tools we use.