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