mach: add mouse motion and mouse button events (#325)

* add mouse motion and mouse button events
* add scroll events
* switch from button/action to mouse_press and mouse_release events

examples/advanced-gen-texture-light/main.zig

@@ -88,6 +88,7 @@ pub fn update(app: *App, engine: *mach.Engine) !bool {
                 },
                 else => {},
             },
+            else => {},
         }
     }