Composition QA

[domyen]

Issue:
This PR polishes Storybook Composition.

What I did

I adjusted the Composition UI so that it matches the design. Also tweaked some Sidebar and Button styles that affected Composition.

How to test

• Is this testable with Jest or Chromatic screenshots? Yes
• Does this need a new example in the kitchen sink apps? No
• Does this need an update to the documentation? No

Bugs that need fixing

• Sidebar:Dark with refs does not get rendered and snapshotted by Chromatic
• Clicking on a new version collapses the ref when it should not
• "View Docs" link does not work

[domyen]

@ndelangen found some issues that I could use a hand with:

Bugs

• Clicking on a new version collapses the ref when it should not https://www.loom.com/share/5198402e9f7647cb8987cd25be8ff4d1
• "View Docs" link does not work for some reason
  

Reorg "Refs" stories for visual testing
Instead of having all the refs states printed in Sidebar:With Refs, can we decompose the refs into separate stories? That would make regression detection more granular/effective.

Strawman:

• Keep Sidebar/Sidebar: With Refs, but only show one representative Ref
• Add Sidebar/Refs: ref name for each ref

[ndelangen]

Yes, I'll work on that @dom
I'll focus on getting #11295 merged first

[ndelangen]

I'm on it now, I'll do:

• "View Docs" link does not work
• Clicking on a new version collapses the ref when it should not
• Reorg "Refs" stories for visual testing