add group sharing to postit

src/logic-scenes/board/post-it.gd

@@ -63,6 +63,11 @@ func replace_with(postit: PostIt):
     self.text = postit.text
     self.voice_line = postit.voice_line
     self.sibling = postit.sibling
+    self.name = postit.name
+    for group in self.get_groups():
+        self.remove_from_group(group)
+    for group in postit.get_groups():
+        self.add_to_group(group)
 
 func _process(_delta: float) -> void:
     _move_post_it()