Improvement: DO-3453 make chat component more flexible and UI updates

[patricia-causalens]

Motivation and Context

Update chat component in order to make it more flexible and with latest design

Implementation Description

• Updated chat component so that it has a non "popup" version that can be used to embed in other places.
• Updated so that messages sent by the user now show in a different color.
• Updated Textarea component so that as you type the are grows for chat component usage
• Added aria roles etc to improve the component's accessibility

Any new dependencies Introduced

None

How Has This Been Tested?

Locally on storybook and a test app

PR Checklist:

• I have implemented all requirements? (see JIRA, project documentation).
• I am not affecting someone else's work, If I am, they are included as a reviewer.
• I have added relevant tests (unit, integration or regression).
• I have added comments to all the bits that are hard to follow.
• I have added/updated Documentation.
• I have updated the appropriate changelog with a line for my changes.

Screenshots (if appropriate):

[krzysztof-causalens]

Would it be more composable instead if you exposed effectively this component without the wrapper (so 'ChatBody', ReplyWrapper + the logic, intended to be rendered directly) as a 'Chat' component and then a 'ChatPopup' which would wrap the first component? Or are the popup visuals partially in dara-components?
Feels like it could be a nicer pattern than having to do conditional styling, this way the place where we use it can choose to use its own wrapper if need be rather than be stuck with the two provided options.

If it's urgent I'm fine with the current approach but I think it could maybe be improved

[patricia-causalens]

That is fair. Will make a separate ticket to look into improving this, but given tight timings will merge this one for now

[tamara-causalens]

Very nice!