Resolve #3054

• Refactor how the current url is checked inside app.vue. This reduces the amount of String.indexOf() calls, and it makes implementing this PR easier.
• Fix a bug where Settings menu item in the sidebar isn't highlighted when viewing the Transformation and Persistence sections.
• Add a new browserTitle config for pages other than the overview page
• Hide "Sidebar & Visibility" and "Tags" input for the overview page. This frees up some screen real estate for editing widgets
• Every page has a custom browser page title:
  • Pages will use its browserTitle || label config
  • Overview page will just use label since it's not used elsewhere
  • For other pages, use the section menu's text, so if/when this gets internationalized, the title will also change
  • Settings -> System Settings will use Settings - <navbar title> - openHAB and so it's also automatically localized as the navbar title gets localized.
  • Settings -> Addon settings will use <navbartitle> - openHAB because the navbar title always starts with "Configure....". Adding "Settings - " in front of it would seem redundant.
  • Things/Items/Widgets/Add-on Store/Pages/Rules/Scripts/Scenes will show [X] - [uid] - openHAB e.g. Things - mqtt:topic:xxx - openHAB