Prevent forwarding only "mouse released" events

Some mouse clicks DOWN are captured for shortcuts, but the matching UP
events were still forwarded to the device.

Instead, capture both DOWN and UP for shortcuts, and do nothing on UP.

PR #2259 <https://github.com/Genymobile/scrcpy/pull/2259>
Refs #2258 <https://github.com/Genymobile/scrcpy/pull/2258>