Rebuild dashboard using Vue/Vuetify and new structure

STEPS

• New backend
• Implement admin view for managing dashboard widgets with successful creating, editing and deleting widgets
• Implement generic dashboard component with
  • support for logged in/not logged in users
  • edit option
• Implement dashboard with integrated edit function
• Implement default dashboard as alternative if user hasn't configured dashboard (with notice)

as concept says

changed milestone to %7a. Dashboard

added part::frontend type::feature type::refactoring labels

assigned to @ZugBahnHof

DashboardWidgetInstance: x,y,width,height (x,y 0-11, w 1-12, h???); one layout for desktop/tablets, on mobile everything 12 cols

x should be 0-11, not y

created branch 1181-rebuild-dashboard-using-vue-vuetify-and-new-structure to address this issue

mentioned in merge request !1707

TODO: Announcement widget (#175 (closed))

TODO #251

changed the description

At FOSDEM, someone reminded me of the feature request to have sub pages. Don't know, if and how this may be integrated into the plan …

what exactly do you mean by that?