issue #5841
- fix relative link checks in navlink url input component
- fix navlink url input component sending absolute URLs instead of relative URLs to action handler
- remove URL manipulation in navigation settings controller (url input handles URL manipulation, validator flags anything that's still incorrect)
- capture cmd-s in url input to ensure changes are actioned before save
- automatically add mailto: to e-mail addresses
- add gh-validation-state-container component so .error/.success validation classes can be applied to any container element
- add validation-state mixin that can be mixed in to any other component to give it access to validation status (used in gh-navitem component to keep alignment when inline error message elements are added)
- validate and display inline errors on save
- improve ember test coverage for navigation settings related controller and components
