Use an overlay window for window resizing

Also implement a remote command to resize windows

kittens/tui/loop.py

@@ -236,7 +236,9 @@ class Loop:
                 self.handler.on_text(chunk, self.in_bracketed_paste)
 
     def _on_dcs(self, dcs):
-        pass
+        if dcs.startswith('@kitty-cmd'):
+            import json
+            self.handler.on_kitty_cmd_response(json.loads(dcs[len('@kitty-cmd'):]))
 
     def _on_csi(self, csi):
         q = csi[-1]