refs https://github.com/TryGhost/Team/issues/1376
- adjusted tests so they are in sync with expected dashboard behaviour
- removed `dashboardHideGettingStarted` feature and it's usage in the `showMembersGraphs` property as there's no longer a resource box to dismiss
refs https://github.com/TryGhost/Team/issues/1406
- added fetch of a single member to the dashboard initialisation if we don't already have some members loaded in memory
- added `showMembersGraphs` getter used in the conditional for rendering the members graphs block component
- if `improvedOnboarding` flag is disabled, return `showMemberData` so existing functionality is retained
- will return `false` if until the single-member fetch has completed if we don't already have any members in memory
- returns `true` if any members exist or the "get started" dashboard resources block has been dismissed
no issue
- adds blank `/dashboard` route ready for future 4.0 related changes
- `/` now redirects to `/dashboard` instead of `/site`
- adds "Dashboard" link to main nav menu
