When selected custom menu is removed, go to settings menu
Allow iframe in custom menu to use Scripting API
Return menu object when it is registered, can call remove function on it
Generally speaking, I like to call the message at the bottom an "action message".
And things can "trigger" it, but in the case of a method that actually proactively displays the message, I find "displayActionMessage" to be a better name.
Also, removing package-lock files and improving code style
