Refactor SVC handler (#540)

* Refactor SVC handler

* Get rid of KernelErr

* Split kernel code files into multiple folders

Ryujinx.HLE/HOS/Kernel/Threading/KEvent.cs

@@ -0,0 +1,14 @@
+namespace Ryujinx.HLE.HOS.Kernel.Threading
+{
+    class KEvent
+    {
+        public KReadableEvent ReadableEvent { get; private set; }
+        public KWritableEvent WritableEvent { get; private set; }
+
+        public KEvent(Horizon system)
+        {
+            ReadableEvent = new KReadableEvent(system, this);
+            WritableEvent = new KWritableEvent(this);
+        }
+    }
+}