Allow non-http(s) urls for applications

**Is your feature request related to a problem? Please describe.**
We host multiple game servers which allow steam links `steam://` to open them from the browser directly.
Currently the Application system does not allow us to use said links, which is a shame.

**Describe the solution you'd like**
Allow non https links for applications, so users can be offered non-webpage links as well.

**Describe alternatives you've considered**
Having to host some sort of forwarding, which is convoluted at best