Improve Notifications

[alexpaxton]

Closes #480

Most of this code is for the notification documentation. There are only minimal changes to the component.

Changes

• Add a z-index property to the notification portal
  • Prevents it from getting covered up by FunnelPage
• Fix a bug that was causing some heinous text wrapping
• Add random notification generator to documentation
  • Makes it easier to test all the permutations of props
• Create a hipsum generator
  • Useful for testing components that display text in any amount

Screenshots

Checklist

Check all that apply

• Updated documentation to reflect changes
• Added entry to top of Changelog with link to PR (not issue)
• Tests pass
• Peer reviewed and approved
• Signed CLA (if not already signed)