Dmm/upgrade design system to 9.0

[Sgtpluck]

Relevant Ticket or Conversation:

There's a new LGDS!!!!

Description of Changes:

The only big changes I could identify were:

• Updates the header to the proper colors
• Adds an image that was removed from the design system
• Updates the menu close mobile nav button to an icon
• Adds a helper module to include usa-current class when necessary

During the course of this change, I also:

• Created a nav partial to make it easier to work on the navigation

  PR Checklist:

1. [ ] Have you linted and tested your code locally prior to submission?
2. [ ] Have you tagged the appropriate dev(s) for review?
3. [ ] Have you linked to any relevant tickets or conversations?

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