Adds namespace support to the UI:
1. Namespace CRUD/management
2. Show Namespace in relevant areas (intentions, upstreams)
3. Main navigation bar improvements
4. Logic/integration to interact with a new `internal/acl/authorize` endpoint
* Begin refactoring CSS into component folders. Moved most
components into layout/skin folders, left out a couple of ones I want
to think about more.
* Adjust grays based on recent Structure changes
* Switch to fullscreen layout for lists and detail, left aligned forms (#4435)
* Specifically use the 'actions_close' label, not just the :last-child (actions-group)
* Replace some non-var-ed colours in vaults code skin, plus prefixing (black and white)
