Changes in public url format requirements have broken SSO callback urls

[tapioca-sublime]

The changes introduced in #3862 have broken SSO callback urls when using GUI.base_path

This is because the following condition in frontend.go requires /app/index.html to be appended to the public url

 if !strings.HasSuffix(config_obj.GUI.PublicUrl,
				config_obj.GUI.BasePath+"/app/index.html") {

Resulting in /app/index.html to be inserted in the middle of the callback url which is set up in bin/config_interactive.go

	case "GitHub":
		redirect = config_obj.GUI.PublicUrl + "auth/github/callback"
	case "Azure":
		redirect = config_obj.GUI.PublicUrl + "auth/azure/callback"
	case "OIDC":
		redirect = config_obj.GUI.PublicUrl + "auth/oidc/callback"

The redirect url in SSO provider must match the callback url supplied by Velociraptor. The registration is still successful, however, you are then redirect to an invalid page (e.g. https://www.example.com/velociraptor/app/index.html/velociraptor/auth/azure/callback?code=token_token_token_token which give a 404 error) and you need to manually modified the url (e.g. to https://www.example.com/velociraptor/auth/azure/callback?code=token_token_token_token)