Issue #8084: DesktopGL GraphicsDevice.ScissorRectangle Fix (#8284)

* Fixed ScissorRectangle Bug Noted in Issue #8084

The fix to this problem was testing to see if the ScissorRectangle was enabled and resizing it whenever the viewport was resized. This was not done by default for DesktopGL as far as I could tell.

* Resolving comments from PR.

Resolving Simon's comment with regards to the placement of the conditional.

MonoGame.Framework/Platform/SDL/SDLGameWindow.cs

@@ -299,6 +299,10 @@ public void ClientResize(int width, int height)
                 _game.GraphicsDevice.PresentationParameters.BackBufferHeight == height) {
                 return;
             }
+
+            if (_game.GraphicsDevice.RasterizerState.ScissorTestEnable && _game.GraphicsDevice.ScissorRectangle == _game.GraphicsDevice.Viewport.Bounds)
+                _game.GraphicsDevice.ScissorRectangle = new Rectangle(0, 0, width, height);
+
             _game.GraphicsDevice.PresentationParameters.BackBufferWidth = width;
             _game.GraphicsDevice.PresentationParameters.BackBufferHeight = height;
             _game.GraphicsDevice.Viewport = new Viewport(0, 0, width, height);