wezterm.mux.get_window(WINDOW_ID)
Since: 20220624-141144-bd1b7c5d
Given a window ID, verifies that the ID is a valid window known to the mux and returns a MuxWindow object that can be used to operate on the window.
This is useful for situations where you have obtained a window id from
some other source and want to use the various MuxWindow
methods with it.