Router: Support RegExp in Route component

[ndelangen]

This targets release/7.2 to not disrupt the 7.1 release.

What I did

• I made the router library more powerful by making the Route component accept a RegExp as a path prop.
• I improved the Route component interface

How to test

• unit tests should pass
• types check should pass
• no UI changes
• e2e tests should pass
• generating a sandbox and navigating from default path (/) to a story, then to settings page should work.

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]