Closable top banner

[amirrustam]

• Add a close "X" icon to the right-end of the top banner to allow users to close the top banner.
• Utilize localStorage to cache the user's decision to close the banner.
• Caching of closed banners should be done for each unique banner, and should not apply to all banners.

[amirrustam]

@KateAbramova the close link can use a big of refinement on mobile:

I got the above shot from the test run video. The close icon should have similar left padding to the rest of the content.

[amirrustam]

@TonySynenko please check off the todo items within the issue as you're working on it or before the associated PR gets merged. Thank you.