Define styling workflow/process for components

[erichuffman]

Considerations:

• Amount of styling to include. At a minimum whatever is required to fulfill functional requirements (e.g., an accordion-like component requires toggling the visual display of elements). Additional styling for demonstration purposes (a component's Storybook listing) should be optional.
• Best method for accommodating 3rd party classes (i.e., define a standard process/technique for allowing utility classes to be applied to components.)

Definition of done:

• A working example of how styling for a component would be structured so that only required styling (if needed) is available to be packaged separately from styling that's used for its display in Storybook
• Working example should also show a best practice for accommodating utility classes from a 3rd party system (USWDS, design.cms.gov, etc.)
• Add relevant documentation where applicable to the docs section of Storybook (like a "styling" section under a "component guidelines" section, etc.)