Recurse group memberships for group add/delete/sync license command

**Is your feature request related to a problem? Please describe.**
It would be very helpful to be able to use a group of groups when managing licenses. For example, if group allemployees contains groups DepartmentA, DepartmentB, and 20 individual users, right now it is necessary to run 3 commands to add licenses:

gam group allemployees add license x
gam group DepartmentA add license x
gam group DepartmentB add license x

And there is no way to use the sync command in this scenario, because if you "gam group all employees sync license x" then it will remove all the licenses for the subgroup members.

**Describe the solution you'd like**
When gam prepares the membership list, I would like it to recurse through sub-group memberships and apply the command to all subgroup members.

**Describe alternatives you've considered**
We have considered scripting a process that flattens the groups in question and creates a temporary group. We have also considered creating ERP integrations that create flat groups in our on-premise environments which would then be synced using GADS, and then could be used for license management.

**Additional context**
Add any other context or screenshots about the feature request here.