UI Enhancement/Feature: Display Unified Sonarr/Radarr Calendars in the Seerr UI

[buttcheekz]

This is a feature request for an enhancement to the Seerr UI to integrate with the release calendars in both Sonarr and Radarr and display them as one unified calendar in the Seerr UI.

While I as an admin have access to my Sonarr and Radarr release calendars, my users do not. Most also do not have Discord accounts and would not be interested in subscribing to a notification-style feed. (Think older family members, non tech-savvy people, etc.)

However, they do have access to Seerr in their browsers for requests; so I feel like this would be a great place to embed those calendars.

The ability to filter by requester, media type, tags, and release type would be huge for them to view upcoming requests. I had considered mentioning iCal feed URLS, but Sonarr and Radarr both already support that so it may be redundant.

I have done a search for similar suggestions and found this is also somewhat related to #2354 - but it is less about RSS updates or summaries of releases, and more about being able to view an interactive calendar from the Seerr UI.

[fallenbagel]

#672