Extend client to support alerting schedules, users, etc

[TSkrebe]

It seems like client only allows a team to be a responder, while api support schedule, escalation and user alerting.

[TSkrebe]

is this a missing feature or is there another way to achieve this? cc @msingla2 since you have contributed recently

[msingla2]

@TSkrebe I'll check it and then let you know the same