Windows Fullscreen Fixes (#87)

This PR fixes two bugs introduced in #80 :
- Exiting fullscreen could exit the Ryujinx window  (https://github.com/Ryubing/Issues/issues/415)
- Toggling fullscreen on would move the window to the primary monitor

And two other bugs related to input view :
- Exiting fullscreen when window was previously in a non maximized state now conserves the window coordinates and size properly (https://github.com/Ryubing/Issues/issues/425)
- Opening the ryujinx app no makes the app grow slightly larger vertically on each launch (+31px on my 1080p monitor) (https://github.com/Ryubing/Issues/issues/425)

Reviewed-on: https://git.ryujinx.app/projects/Ryubing/pulls/87

src/Ryujinx/UI/Helpers/Win32NativeInterop.cs

@@ -63,6 +63,18 @@ namespace Ryujinx.Ava.UI.Helpers
             }
         }
 
+        [StructLayout(LayoutKind.Sequential)]
+        public struct NativeRect
+        {
+            public int Left;
+            public int Top;
+            public int Right;
+            public int Bottom;
+
+            public int Width => Right - Left;
+            public int Height => Bottom - Top;
+        }
+
         public static nint CreateEmptyCursor()
         {
             return CreateCursor(nint.Zero, 0, 0, 1, 1, [0xFF], [0x00]);
@@ -119,6 +131,10 @@ namespace Ryujinx.Ava.UI.Helpers
         [LibraryImport("user32.dll", SetLastError = true)]
         public static partial nint SetWindowLongPtrW(nint hWnd, int nIndex, nint value);
 
+        [LibraryImport("user32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        public static partial bool GetWindowRect(nint hWnd, out NativeRect lpRect);
+
         [LibraryImport("user32.dll", SetLastError = true)]
         [return: MarshalAs(UnmanagedType.Bool)]
         public static partial bool SetWindowPos(