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
- Adds full set of svg icons as CSS/Sass variables to the source
- Starts picking out some frame-grays, whilst commenting in possibles
- Remove color prefixing
The prefixes `ui-` and `brand-` for colors hav been removed. This makes
colors slightly easier to type.
In order to differentiate between brand colors and 'normal' colors, normal
colors are named as 'true colors' i.e. blue, red, green etc etc
whereas the brand colors used a more premium sounding name such as
'steel' for vault gray, 'magenta' for consul, 'cobalt' for vagrant etc etc.
* 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)
John Cowen