Add the ability to collapse or expand the nav manually

[nlitwin]

Perceived Problem

• When a user's screen size is just above the desktop breakpoint, they may want to collapse the nav in the dashboard to have more room for writing.

Ideas / Proposed Solution(s)

• Issue Dashboard Nav should be delightfully animated and responsive #35 outlines a potential solution. A chevron could be added to the nav for tablet/desktop screens which allows expanding/collapsing the nav.
• Some things to handle when implementing:
  • Allow users to collapse/expand the nav on tablet/desktop breakpoints, even though changing the screen width automatically puts the nav back into a collapsed or expanded state depending on the breakpoint.
  • Handle cases where certain pages require a collapsed nav (like the settings page)