chore(docs): Add demo for canvas

[rebeccaalpert]

Fixes #899

See https://chatbot-pr-chatbot-901.surge.sh/extensions/chatbot/overview/demo/canvas/ for demo.

[patternfly-build]

Preview: https://chatbot-pr-chatbot-901.surge.sh

A11y report: https://chatbot-pr-chatbot-901-a11y.surge.sh

[kaylachumley]

Thanks for working on this! This is looking really good. A few notes/adjustments per our discussion from yesterday.

• Make the "generated by AI" label clickable with a popover that's initiated upon click. Here is a screenshot of the text that needs to be in the popover:

• I spoke to nicole about where this demo could live for better visibility and we agreed that it would fit nicely under our Patterns section in the left nav. Can you change the section field in the meta data so this lives under patterns?

• Add in a redo and undo action(icon button) in the code editor toolbar

• Add in a export icon button in the code editor toolbar

• Add in a save icon button in the code editor toolbar

• Add an "x" icon button into the left chatbot header

• Add in the original history drawer icon button in the chatbot header

• Add the "Always review AI-generated content prior to use." footnote below the message bar

[rebeccaalpert]

I'm pushing a commit because it's easier for me to look at here, but I am still working on scoping the styles a little better with the drawerception thing. We are currently a little screwed up. I will work on it some more on Monday.

Also likely want to control focus, but that's complicated by none of the drawer things allowing ref forwarding. May be worth waiting to do that until we can add that in.