GH-2211: Onboarding - Status Bar

[benstrumeyer]

• Have you followed the guidelines in CONTRIBUTING.md?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do?
• Does your submission pass tests?
• Did you lint your code prior to submission?

• Create StepProgressBar component for ghostery-browser-intro-hub
• Routes should be changed inside the steps object of the StepProgressBar.jsx component
• A container div should be used to specify the width since the component is flexible
• Dotted lines sometimes get cut off depending on width, workaround can be to specify a container width, but left flexible for now
• Dotted line solution from: https://stackoverflow.com/a/53408182
• Example Usage: <StepProgressBar currentStep="2" />

Ticket: https://ghostery.atlassian.net/browse/GH-2211

[wlycdgr]

LGTM for merging into intermediate branch purposes