Resolve #3478347 "Add stories files"
Closes #3478347
Adds stories for components:
- case_study_slideshow
- grid_list
- stats_list
- testimonial
Removes the unused Nav component.
Includes some small upstream changes from the 2.x branch that aren't on the palantir branch yet. Or at least, weren't at the time this MR was created.
Fixes a minor style bug on testimonials.
Testing steps:
- spin up storybook and examine each of the above listed components
- verify that they are rendering correctly in their actual story. Things may look 'off' on the story preview.
Edited by jayme johnson