Draft: Replace navigation sidebar with project selector in header
Replaces the sidebar navigation with a project selector in the page's header bar.
- Basic functionality works
- New menu item for "Select a Project"
- Menu item styling adjusted for new context
- New menu item for showing currently selected project
- Refactor menu item code for stronger separation of view and model, need to pass in view attributes or compose them better
- "Add new +" menu item at bottom of context
- Handle very long lists of projects (probably will punt for this PR)
- Sidebar is now gone
- Project selector is now present
- Main content area has max width and visually centered, which is more responsive than before)
- Exosphere branding navigates to