"Show menubar" button enhancements

I'd like to gather insights to help with the decision-making process. Let's discuss potential changes to the show menubar feature slated for 4.18 here

Some alternatives to the current implementation of the show menubar button:

1. Allow the show menubar button to be hidden and repositioned with toolbar editor

   • in it's current state it is always shown and occupies first slot on the menubar
   • problem: potentially unwanted for users that know their keyboard shortcuts
   • solution already exists as out of tree patch (see here)

2. Expose menu functionality in show menubar "hamburger" menu (the way Dolphin or Pragha do it)

   • would allow menubar items to be displayed with minimal space usage
   • should we expose it as an option in the settings as an alternative to menubar toggle functionality
   • should this hamburger menu be...
     • repositionable?
     • fixed to first position in the toolbar?
     • fixed to the last position in the toolbar?

example hamburger menu

Care of @lastonestanding @alexxcons