Progress: smallChevronLink component used on section progress

[Erin007]

Spec item: Add a link for “View course” to the top right that takes the user to the corresponding unit overview page.

Changes in this PR:

1.) A SmallChevronLink component, we use these teal links all over the place and componentizing it might make it more re-usable in the future.
A few places we could re-use this:
- CourseCards on the signed in homepages
- ContentContainer
- top navigation links in teacher dashboard, such as "view all sections"

2.) A Story for SmallChevronLink that also includes its sibling componentLargeChevronLink

• combine large chevron and small chevron components - they are basically the same...
• include RTL versions in Storybook

3.) Use SmallChevronLink on progress tables

Still to do:

• link actually goes where it should
• Should say “View unit” if the script is actually a unit inside a larger course, e.g. /s/csp1 inside /course/csp)

[caleybrock]

This looks awesome. Big fan of the reusability. Code and screenshots look great. 💯

[caleybrock]

I noticed this got changed in the other PR too, intentional?

[Erin007]

My guess is it floated around when I was fixing a merge conflict. Since we want the legend at the bottom of the view, I moved it.