Remove the old Ghsotery Setup page and all its related code

[IAmThePan]

I removed all the code that was part of the old Setup workflow.

• everything in app/setup
• the setup template file: app/templates/setup.html
• the setup scss file: app/scss/setup.scss
• relevant message handlers in src/background
• a ping in src/classes/Metrics
• jsdoc.json
• the relevant compile files in webpack.config.js
• all the setup_... strings in _locales/en.
  • I had to rename one string that was used elsewhere. (setup_footer_license -> license_footer in app/licenses/Licenses.jsx)
  • I had to update a string to not use a deprecated string (setup_button_done -> hub_setup_nav_done in app/hub/Views/SetupViews/SetupBlockingDropdown/SetupBlockingDropdown.jsx)

@christophertino Please check if I need to remove any additional files.