Move admin nav to sidebar

[dracos]

Moves the navigation to a sidebar, and makes it prettier

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.65%. Comparing base (c991bc1) to head (3df276e).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5093   +/-   ##
=======================================
  Coverage   82.64%   82.65%           
=======================================
  Files         404      404           
  Lines       31526    31526           
  Branches     5000     5000           
=======================================
+ Hits        26055    26057    +2     
+ Misses       3987     3985    -2     
  Partials     1484     1484           

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[lucascumsille]

@dracos I really like it, it looks more tidy and easier to scan.

As a suggestion for the hover effect what do you think if we include a variable for the colour and background, they would have by default $button-primary-text and $button-primary-bg-top. Currently not all the cobrands are overriding those variables, however that is being tackled here, but we stopped working on that PR because we ended just making the change for Surrey, but I could add it to this sprint and finish it.