Explore options to support pausing all the available schedules

[sabbyanandan]

As a CF user, I'd like to have the option to pause-all the schedules, so I can explicitly pause them before upgrading the CF foundation/platform.

Notes:

• Gives me an opportunity to finish all the currently running batch-jobs and plan for a downtime (I need to have downtime, it is a requirement, and I'm OK with it).
• Provides me an option to cleanly upgrade the foundation without having to worry about side effects from tasks getting launched while the platform is being upgraded.
• I can resume the schedules when the platform is successfully upgraded.

Next:

• Investigate to see if there's a pause endpoint in PCF scheduler. If there's none, submit a feature request.
• Study the same functionality in K8s.