feat(Avatar): icon's color customization mechanisms are limited

[kuzhelov]

Feature Request

Problem description

Currently the Avatar's icon color is entirely defined by 'presenceStatus' (for example, for the 'Available' status green color is used). The following problems arise as a consequence

• there is no way to customize these colors by theming
• there is no way to decouple Avatar component from the 'presenceStatus' concept - while status aspect of Avatar could be seen as something more general, not about just providing 'presence' status - it could be about providing 'role' status of the person, as a simple example.

Proposed solution

Customization mechanisms for Avatar's icon should be introduced. At the very least, there should be a way to customize

• icon's colors
• icon itself (whether it is a 'shevron', 'pause', 'play', etc)

[kuzhelov]

with current approach to styling this issue is resolved.