When trying to detailed description of AAD membership groups using API getbyids: https://github.com/microsoftgraph/microsoft-graph-docs/blob/master/api-reference/v1.0/api/directoryobject_getbyids.md if AAD member has more than 1000 group memerships

AAD returns:
    "code": "Request_BadRequest",
    "message": "Number of included identifiers cannot exceed '1000'.",

Therefore, guard needs to do page queries to get details of all groups the user belong to. But getbyids does not support query options like $top and $expand and returns error:

    "code": "Request_BadRequest",
    "message": "The following query options are not supported by this request method or cannot be applied to the requested resource: $filter,$expand,$orderby,$count,$inlinecount,$select,$skiptoken,$skip,$top"

So in this case guard cannot rely on AAD to do paging and needs to do paging itself to fetch membership group details from AAD.

Github issue: kubeguard#132

- Avoid re-allocations for groupNames array
- Simplify the loop over groupIDs
- glog.Infof appends \n automatically

…nique objectId for auth

Azure AAD auth provider is using AAD group's displayName instead of unique objectId for auth