Accordion Enhancements

[dillonemorris]

• Change default Accordion to one that has no drawers open on page-load
• Update chevron color to gray["500"]
• Include an option to "expand all" (ex. sidebar of Gatsby Docs sidebar https://www.gatsbyjs.org/docs/)

[erwstout]

@dillonmorris91 do you think you can get to this before the 1.0.0 release or should we add it after?

[erwstout]

~Include an option to "expand all"~

After discussion, we will not implement that at this time