Update USA Banner component

[katyasoup]

resolves #33

What this PR changes:

• adds a new route to enable htmx swapping for show/hide functionality on the USA banner dropdown content
  • updates templ template to accept a parameter for showing/hiding the banner contents
• updates "Here's how you know" clickable element:
  • replaces the <a> element with a <button> element for better keyboard navigability
• updates styles to match the banner at https://www.cdc.gov/phin/php/vocabulary/

How to test:

• Test at both full browser screen width (> 1000px) and smaller responsive widths ( < 900px)
• Click "Here's how you know" and make sure the content properly shows/hides and styles do not change
• Make sure you can interact with the clickable element with both a mouse/trackpad click, as well as tabbing to it and clicking with the space/enter key

Notes:

• Keyboard navigability needs additional work; when using the keyboard to show/hide the banner content, focus should remain on the button element; currently you need to tab backwards to be able to focus and click it again. I'll add another ticket for this.

Feedback requested:

• How can we use the Templ templating instead of creating additional HTML files to use with HTMX functionality? addressed in 99cbe18

[katyasoup]

@nickclyde updated d2aac37 per our convo!

[nickclyde]

This looks great! You could simplify it even further by removing this if statement and just doing component = components.UsaBanner(action)!

[katyasoup]

💡 done!

[nickclyde]

Looks great!!

[akintner]

LGTM 🚀