Add shortcut to reset video capture/encoding

Reset video capture/encoding on MOD+Shift+r.

Like on device rotation, this starts a new encoding session which
produces a video stream starting by a key frame.

PR #5432 <https://github.com/Genymobile/scrcpy/pull/5432>

server/src/main/java/com/genymobile/scrcpy/video/ScreenCapture.java

@@ -291,4 +291,9 @@ public class ScreenCapture extends SurfaceCapture {
             }
         }
     }
+
+    @Override
+    public void requestInvalidate() {
+        invalidate();
+    }
 }