Adding a more robust Admin Settings GUI

[sirkorgo]

Is your feature request related to a problem? Please describe.

I just created an OpenCloud instance, after switching from Nextcloud. Something I noticed, is the lack of customization and server management options in the Admin Settings app on my instance. It's incredibly tedious to have to sift through the documentation to find the necessary environment variables to update that specific setting.

Describe the solution you'd like

Add more options in the Admin Settings app on the instance webpage. Some examples include:

• Theming options: Add the ability to change the favicon, logo, name, and slogan/motd of the instance right from the Admin Settings app.
• Server configuration: add a page to the Admin Settings app, or multiple categories that allow admins to toggle and configuration options in their OpenCloud instance.

Describe alternatives you've considered

Alternate Solutions:

1. A CLI utility to allow admins to configure the server in one place.
2. A global config json file or yaml (does that already exist? I'm not sure about that)

I've tried to configure OpenCloud by setting environment variables, but haven't been able to succeed.

Additional context

N/A