[client] X11: synchronize keyboard input state

Replay held keys after focus enters the client window.

Track modifiers and lock LEDs for cooked and grabbed raw input.

Handle external XKB indicator changes while the window stays focused.

client/displayservers/X11/x11.h

@@ -64,6 +64,10 @@ struct X11DSState
 
   int                   minKeycode, maxKeycode;
   _Atomic(unsigned int) keyboardGroup;
+  int                   numLockIndicator;
+  int                   capsLockIndicator;
+  int                   scrollLockIndicator;
+  int                   xkbEvent;
 
   //Extended Window Manager Hints
   //ref: https://specifications.freedesktop.org/wm-spec/latest/