Support for more flexible thresholds in Alerts escalations

Currently, time-based escalation cannot be set to less than 5 minutes. In most cases, this threshold is pretty high for sensitive API checks. I'd highly appreciate it if you could make it more flexible.

    time_based_escalation {
      minutes_failing_threshold = 5 // (TIME_BASED escalation only) after how many minutes spent in failing state to send an alert ()
    }

As of now, it can be set to 5, 10, 15, 30 minutes

The requested thresholds are, 1, 2, 3, 4, 5 minutes

Reference: https://www.checklyhq.com/docs/terraform-provider/alerting/#alert-settings