masthead accordion

[RCopeland]

What does this PR do?

Masthead updates

Please check off completed items as you work.

If a checklist item or section does not apply to your PR
then please remove it.

Documentation

• Update Spark Docs Angular
• Update Spark Docs Vanilla
• Update Component Sass Var/Class Modifier table

Code

• Build Component in Spark Vanilla (Sass, HTML, JS)
• Build Component in Spark Angular
• Unit Testing in Spark Vanilla (100% coverage, 100% passing)
• Unit Testing in Spark Angular (100% coverage, 100% passing)

Accessibility

• New changes abide by accessibility requirements

Browser Testing (current version and 1 prior)

• Google Chrome
• Google Chrome (Mobile)
• Mozilla Firefox (Mobile)
• Microsoft Internet Explorer 11 (only this specific version of IE)
• Microsoft Edge
• Apple Safari
• Apple Safari (Mobile)

Design Review

• Design reviewed and approved

Screenshots

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expected.