Revised navigation: app navigation tabs

[jduss4]

Implement application navigation using placeholder tabs. Focus on the display and behavior of the nav menu, rather than on the content. See the figma designs for details 🔐

The behavior of the organizations dropdown is out of scope for this issue. Instead, just relocate the current organization header information.

Widescreen [alt: top navigation with a dashboard logo, current organization, and three tabs for product sections]

Small screen [alt: small screen version where the organization is now on the left and there is a hamburger menu on the right]

[alt: small screen version with hamburger menu expanded to reveal the same three placeholder product sections]

Acceptance Criteria

• [ ] Application navigation follows USWDS guidance for menus (see templates)
• [ ] Navigation changes to hamburger menu on smaller screens
• [ ] Organization display behavior remains the same but is relocated
• [ ] Passes manual accessibility testing

[echappen]

Should finish by end of next increment in order to have navigation ready for further usability testing