allow expanding the left side menu
I use a 1080x1920 screen for browsing and the left side menu only shows icons up to 1200px(?).
Especially when learning gitlab, the left side menu icons are not enough, not only because some items use equal icons.
It makes sense to collapse it, especially on very small screens but please don't hide the expand button. Issue or Merge Request counts are also interesting to see by some means.