Feat: DO-3455 accept to optionally pass icon color for user bubble

[patricia-causalens]

Motivation and Context

Allow greater customisation of user bubble on an user level

Implementation Description

Added two new params to UserData which allows one to set the color and what to render within the bubble for the user message.

Any new dependencies Introduced

How Has This Been Tested?

PR Checklist:

• [x] I have implemented all requirements? (see JIRA, project documentation).
• [x] 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):

[patricia-causalens]

Oops accidentally got the branches mixed up and merged some of these changes in the other PR that was just merged :sweat_smile: so the difference is not showing, it is in the user bubble commit if that helps.