macos: implement client side modifier events

closes #198
closes #199

input-capture/src/wayland.rs

@@ -648,16 +648,10 @@ impl Dispatch<wl_seat::WlSeat, ()> for State {
             capabilities: WEnum::Value(capabilities),
         } = event
         {
-            if capabilities.contains(wl_seat::Capability::Pointer) {
-                if let Some(p) = state.pointer.take() {
-                    p.release();
-                }
+            if capabilities.contains(wl_seat::Capability::Pointer) && state.pointer.is_none() {
                 state.pointer.replace(seat.get_pointer(qh, ()));
             }
-            if capabilities.contains(wl_seat::Capability::Keyboard) {
-                if let Some(k) = state.keyboard.take() {
-                    k.release();
-                }
+            if capabilities.contains(wl_seat::Capability::Keyboard) && state.keyboard.is_none() {
                 seat.get_keyboard(qh, ());
             }
         }