Task pause schedule (CE part)

[schmichael]

CE portion of the enterprise Task Pause Schedules feature. WIP.

Sample jobspec:

job "example" {
  group "haha" {
    task "business" {
      schedule {
        cron {
          # Start 9:30am EST Weekdays
          start = "0 30 9 * * MON-FRI *"

          # Stop 4pm EST Weekdays
          stop = "0 0 16 * * MON-FRI *"

          # Start and Stop are EST timezone
          timezone = "EST"
        }
      }

      driver = "raw_exec"

      config {
        command = "/bin/bash"
        args    = ["-c", "echo running; date; sleep 90000"]
      }
    }
  }
}

[gulducat]

closing in favor of #22201