Implement Side Navigation

depends on #33 (closed)

Add the usa-sidenav component to the the template,
https://designsystem.digital.gov/components/side-navigation/

To Do:

• create navigation component
• Add in application navigation to the template (content will be duplicated)
  • Add above primary navigation in header
  • Add to left of main content in page content
    • side navigation will be hidden on mobile
• add example to example project