Site updates feb2024

[jegra]

Updates including the following:

• Add support for linking out to Ludwig and Gray sites from the Atlases page
• Remove description pages (relevant info will be on destination sites)
• Add accessibility link to footer
• Video cards and video carousel
• YouTube video support option (replaced YouTube embed on Talks page with new youtube-card.html include)
• Non-Minerva story card buttons (cellxgene, broad single cell, other)
• Update usage of external image links on data cards (previously, placeholder image was layered underneath the loaded image)