Add expander component

[chromaticWaster]

Description:

Add Expander and Expander Group components

closes #159

• Added the Expander and Expander Group components.
• Added visual and behaviour tests.
• Added relevant stories.

(Link to bug/feature from Issues and how you resolve it)

Screenshots (if appropriate):

Expander

Expander.mov

Expander Group

ExpanderGroup.mov

Expander test results

Expander Group test results

All Submissions:

• I have followed the contribution guidelines for this project.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.

Changes to Core Features:

• I have added an explanation of what my changes do and why I would like to include them.
• I have written new tests for my core changes, as applicable.
• I have successfully ran tests with my changes locally.
• I have added/updated docs, as applicable.