Redesign Wizard and Menu

[Heiss]

• [x] Menu is not visible as long as the wizard was not processed
• [x] Menu gets a gear icon in footer, so there can be added settings things
  • [x] set light / dark mode as icons like vuetify documentary
  • [x] account management link to redirect to an iframe, so the user can be informed about the consequences of an account removal
• [x] multiple iframes on website
  • [x] welcome page (before setup / wizard workflow)
  • [x] help page
  • [x] start page (after setup / wizard)
  • [x] account removal page (when the user wants to delete the RDS account)
• [x] "jetzt starten" on welcome page redirects to oauth2 owncloud page
  • [x] after successful activation, the user will see the services view without any menu (with the v-card on top for informations)

[juriroemer]

• [x] expension panels have a description of the services, which will be set through the port in backend