High contrast theme support

[mcoker]

Problem statement

Users with specific vision requirements find the interface difficult to read and navigate because the existing theme lacks sufficient color contrast. "As a PatternFly user, I would like to have more accessible options for my vision requirements. (from patternfly/patternfly-design#1357)"

Goal

Update chatbot styles and any usage documentation/suggestions/demos needed to support products' ability to utilize HC chatbot in their UIs.

Links

• Theming - High contrast theme patternfly-design#1357 - Design epic for HC theme
• ChatBot - Evaluate and Spec out High Contrast Designs patternfly-design#1444 - Design epic for chatbot styles
• Figma design for high contrast

Issues

TBD

[lboehling]

The following custom chatbot components need additional HC border styles:

• ChatBot Container - Overlay
• ChatBot Container - Docked
• ChatBot Modal
• ChatBot History Drawer
• History Menu Items
• Message Bar
• Icon Buttons
• Attachments
• Message Snippets
• User Feedback Cards
• Image Cards
• Source Cards
• Message Divider - Guest Announcement
• Spinner
• Animated Dots

Detailed design specs for the above components can be found here: https://www.figma.com/design/wKcOq7IrzfL1gEK2mocd6r/High-Contrast-Component---Extension-Specs?node-id=12421-109383&t=PQfL5JGxNFuD7qWK-4

FYI @rebeccaalpert @kaylachumley

[mcoker]

Closing in favor of individual issues linked in the main epic - patternfly/patternfly#7724