refs #5798, closes#5018
- adds new `gh-fullscreen-modal` component - modals are now specified in-context so that they can have deeper interaction with their surrounding components/controller/route, i.e. a modal component can be a thin confirm/deny wrapper over the underlying controller action keeping all context-sensitive logic in one place
- adds spin-buttons to all modals with async behaviour
- adds/improves behaviour of inline-validation in modals
- improves re-authenticate modal to properly handle validation and authentication errors
