New: Use ASP.NET Core instead of Nancy

Co-Authored-By: ta264 <ta264@users.noreply.github.com>

src/Sonarr.Http/VersionedApiControllerAttribute.cs

@@ -0,0 +1,34 @@
+using System;
+using Microsoft.AspNetCore.Cors.Infrastructure;
+using Microsoft.AspNetCore.Mvc.Infrastructure;
+using Microsoft.AspNetCore.Mvc.Routing;
+
+namespace Sonarr.Http
+{
+    public class VersionedApiControllerAttribute : Attribute, IRouteTemplateProvider, IEnableCorsAttribute, IApiBehaviorMetadata
+    {
+        public const string API_CORS_POLICY = "ApiCorsPolicy";
+        public const string CONTROLLER_RESOURCE = "[controller]";
+
+        public VersionedApiControllerAttribute(int version, string resource = CONTROLLER_RESOURCE)
+        {
+            Resource = resource;
+            Template = $"api/v{version}/{resource}";
+            PolicyName = API_CORS_POLICY;
+        }
+
+        public string Resource { get; }
+        public string Template { get; }
+        public int? Order => 2;
+        public string Name { get; set; }
+        public string PolicyName { get; set; }
+    }
+
+    public class V3ApiControllerAttribute : VersionedApiControllerAttribute
+    {
+        public V3ApiControllerAttribute(string resource = "[controller]")
+            : base(3, resource)
+        {
+        }
+    }
+}