Added shared UI library and finished the ColorPicker

src/Artemis.Core/JsonConverters/SKColorConverter.cs

@@ -0,0 +1,24 @@
+using System;
+using Newtonsoft.Json;
+using SkiaSharp;
+
+namespace Artemis.Core.JsonConverters
+{
+    public class SKColorConverter : JsonConverter<SKColor>
+    {
+        public override void WriteJson(JsonWriter writer, SKColor value, JsonSerializer serializer)
+        {
+            writer.WriteValue(value.ToString());
+        }
+
+        public override SKColor ReadJson(JsonReader reader, Type objectType, SKColor existingValue, bool hasExistingValue, JsonSerializer serializer)
+        {
+            if (reader.Value is string value && !string.IsNullOrWhiteSpace(value))
+            {
+                return SKColor.Parse(value);
+            }
+
+            return SKColor.Empty;
+        }
+    }
+}