New: Rework and Require Authentication

Co-Authored-By: Mark McDowall <markus101@users.noreply.github.com>

src/NzbDrone.Core/Authentication/AuthenticationRequiredType.cs

@@ -0,0 +1,8 @@
+namespace NzbDrone.Core.Authentication
+{
+    public enum AuthenticationRequiredType
+    {
+        Enabled = 0,
+        DisabledForLocalAddresses = 1
+    }
+}

src/NzbDrone.Core/Authentication/AuthenticationType.cs

@@ -1,9 +1,10 @@
-namespace NzbDrone.Core.Authentication
+namespace NzbDrone.Core.Authentication
 {
     public enum AuthenticationType
     {
         None = 0,
         Basic = 1,
-        Forms = 2
+        Forms = 2,
+        External = 3
     }
 }

src/NzbDrone.Core/Configuration/ConfigFileProvider.cs

@@ -34,6 +34,7 @@ namespace NzbDrone.Core.Configuration
         bool EnableSsl { get; }
         bool LaunchBrowser { get; }
         AuthenticationType AuthenticationMethod { get; }
+        AuthenticationRequiredType AuthenticationRequired { get; }
         bool AnalyticsEnabled { get; }
         string LogLevel { get; }
         string ConsoleLogLevel { get; }
@@ -192,6 +193,8 @@ namespace NzbDrone.Core.Configuration
             }
         }
 
+        public AuthenticationRequiredType AuthenticationRequired => GetValueEnum("AuthenticationRequired", AuthenticationRequiredType.Enabled);
+
         public bool AnalyticsEnabled => GetValueBoolean("AnalyticsEnabled", true, persist: false);
 
         public string Branch => GetValue("Branch", "master").ToLowerInvariant();