Basic Nav component

[sagarvxyz]

The Nav component should:

1. Display a nested hierarchy of test components
2. Allow users to click components that change what's displayed in the FormDisplay
3. Collapse and expand children of parent components (like a folder in VSCode)

Design notes:

1. It should be no more than half the width of the FormDisplay app
2. It should collapse into a menu when the screen cannot fit all 3 components side by side
3. It should cast a slight shadow on the FormDisplay to give the app depth
4. It should highlight the active test component.