Command to create AAD groups

If the approach is to create a Maintainers/Admins GH team for each team project, then map those to AAD groups. The way it works now is the customer has to create the AAD groups in advance, then the CLI will do the GH Team linking. Would probably be better if the CLI had the capability to also create the AAD groups as part of the migration process.

This will require credentials to be able to write to AAD (i.e. service principal client id/secret).