[Feature Request] Monitor upstream status pages: RSS/Atom feed monitor and provider presets

📑 I have found these related issues/pull requests Earlier requests for monitoring external status pages • #1490 Ways to integrate external status pages? Closed as stale in 2023, without a built-in solution. • #4665 Incorporate a status page offered by an external service. Resolved with a JSON Query monitor for one provider. Config templates were suggested for the general case. • #4619 Atlassian status page monitor (PR). Closed. The concern was that one monitor per provider is not maintainable, and config prefabs were suggested instead. • #6139 Monitor type for upstream status pages. Closed as a duplicate, because too many status page APIs exist to support. Related direction • #1323 Config templates. Open. The presets in this request could build on it. • #1089 Dependent monitoring of hierarchical monitors. Open. It was suggested in #6139, but it covers monitors within one instance rather than third-party providers. Different scope: Uptime Kuma p…