Alter personal host assignment mechanism to reduce assignment counts

For personal host pools, when you assign a user to a personal session host, Nerdio creates a net new assignment to the SessionDesktop Application Group. However, this does not coincide with the capability in the AVD management portal (native), where you can assign a group of users to the application group and then assign a user from the group to a designated host without creating a brand-new assignment. 

I feel that Nerdio should be updated to reflect this behavior as we are assigning groups to the personal host pool but each time we assign a user to a session host, it creates a brand new assignment. Maybe this was intentional but it seems.. messy.