dxp/issues#1744: style AI chat interface for XIAiChat style

Changes

Figma: https://www.figma.com/design/czbmVcvkppBSspZ9h72QDD/1x_AI_Solution_2025?node-id=1-4&p=f&t=EwLmSKabXG0FnLNd-0

• Adds styling for Inline and sticky versions of the chatbot based on the Figma design under the 'XI Ai Chat' assistant style file
• Adds toggling functionality for sticky chat
• Adds default configuration which matches the design
  • Default Message
  • 1xChat style
  • Default bot image
  • Stream set to false (This is needed for overlay to work nicely)
  • Inline placement
  • Bot name