feat: web UI for adding radio stations

[tomassasovsky]

Description

We should have a command called /radio add that lets users add radio stations to the RadioBrowser DB from a webpage.

Requirements

• When running the /radio add command, users should get a prompt to open our Web UI.
• They can fill up a form to add the radio station and all its data.
• If they don't know the necessary radio station data, they can submit a form for the support team to find the data and complete it themselves.

[tomassasovsky]

@NazarenoCavazzon Assigning this to you! You can see something similar here