Create OpenSearchCon NA 2024 save the date webpage and add to top-nav

[pajuric]

Create OpenSearchCon North America 2024 webpage to start collecting interest and to tease "save the date."

• Add OpenSearchCon NA to the top navigation
• Build page using the OSCon EU page as the example
• Create page banner using design provide by team
• Add CTA to capture leads (TBD)
• Include social sharing buttons and icons to start promotion

Page should be ready to launch by May 1, 2024.