Fixing more warnings (#5189)

* classes need to be in new files

* adding in new lines

Co-authored-by: Clint Rutkas <crutkas@microsoft.com>

src/core/Microsoft.PowerToys.Settings.UI/Interop.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.InteropServices;
+
+namespace Microsoft.PowerToys.Settings.UI
+{
+    internal static class Interop
+    {
+        public static ICoreWindowInterop GetInterop(this Windows.UI.Core.CoreWindow @this)
+        {
+            var unkIntPtr = Marshal.GetIUnknownForObject(@this);
+            try
+            {
+                var interopObj = Marshal.GetTypedObjectForIUnknown(unkIntPtr, typeof(ICoreWindowInterop)) as ICoreWindowInterop;
+                return interopObj;
+            }
+            finally
+            {
+                Marshal.Release(unkIntPtr);
+                unkIntPtr = System.IntPtr.Zero;
+            }
+        }
+
+        [DllImport("user32.dll")]
+        public static extern bool ShowWindow(System.IntPtr hWnd, int nCmdShow);
+
+        public const int SW_HIDE = 0;
+    }
+}