[Feature] Show scheduled maintenance windows on public status page

Summary

Allow maintenance windows to be displayed on the public status page and tied to notifications.

Problem

Users cannot communicate planned downtime windows to the users through the status page. This leads to confusion when services go down for scheduled maintenance.

Proposed Solution

Add option to display maintenance windows on the public status page Stack multiple maintenance windows at the top of the page when applicable Tie maintenance inputs to notification channels Show:

• Maintenance title/description
• Scheduled start and end times
• Affected services/monitors