[Avatar] Backgrounds are hardcoded

[hyyan]

The avatar backgrounds are hardcoded and it is not possible to change them from CSS or through attributes

[saadnoor]

We don't need to change them, they change automatically based on the name. (The color for HYAAN and STEPHAN won't be the same). I think @StephanWald can shed some light on this.

[DominicWrege]

The Background colors should be a property of your component. Of course, It's good to have some default ones, but the user should be able to customize them.

[hyyan]

@saadnoor Make them configurable please