Programatic maintenance windows

## Done Criteria
There is a programatic ability for SPs to specify their maintenance window meaning they can set a time per day for 20 minutes where dealbot won't run checks against them.

This should get set in some place publicly accessible like the SP registry. (Public endpoint is also a possibility.)

https://github.com/FilOzone/dealbot/blob/main/docs/checks/production-configuration-and-approval-methodology.md#sp-maintenance-window should be updated.

## Why Important
SPs need an opportunity to do maintenance.
Our existing daily time concentrates when SPs are doing mentnance which means we're more likely to have no SPs operating during this time

## Notes
1. This builds on https://github.com/FilOzone/dealbot/issues/163
2. There was https://linear.app/filoz/issue/XFN-197/mainenance-window-for-sps-to-indicate-they-do-not-want-to-receive about this in the past