resource pagerduty_schedule does not include final_schedule and rendered_coverage_percentage

[Padorax]

Issue

The PagerDuty schedule API exposes some useful fields that are currently missing from the provider output.

1. rendered_coverage_percentage under schedule_layers.
2. final_schedule with rendered_coverage_percentage.

These fields can help users check whether there are coverage gaps, especially in final_schedules. So they don't miss alerts indeliberately.

Current output

       foo_schedule                = {
           description = "foo_schedule Schedule"
           id           = <schedule_id>
           layer       = [
               {
                   end                          = null
                   id                           = (known after apply)
                   name                         = "Layer 1"
                   restriction                  = []
                   rotation_turn_length_seconds = 604800
                   rotation_virtual_start       = "2019-05-10T11:00:00+01:00"
                   start                        = "2021-03-05T00:00:00Z"
                   users                        = [
                       "<user_id>",
                    ]
                },
            ]
           name        = "foo_schedule"
           overflow    = null
           time_zone   = "Europe/London"
        }
    }

Provider version

terraform {
    pagerduty = {
      version = "1.9.6"
    }
}

[imjaroiswebdev]

Addressed in #528