[AvatarGroup] Add support for avatar grouping

[IraSkyx]

This issue is dedicated to discuss support for a new avatar group component.

• I have searched the issues of this repository and believe that this is not a duplicate.

Summary 💡

Like ButtonGroup does, the component should provide support for grouping avatar with a limited number of visible ones and a property maxCount indicating the "+X" number of other avatar. The "+X" label should provide an on click handler so users can add extra behavior (like showing the whole list of people's avatar).
There is no Material Design spec for this and I've searched on Google to find existing component and have found nothing.

Examples 🌈

Extracted from PeaPods, on MUITreasury :

Motivation 🔦

In the world of social interactions, events, etc... I think this component is worth the implementation, and it's quite easy to do. It is an equivalent for the "X people are going/interested in this Facebook event".

[adeelibr]

Do we need to create a new component for AvatarGroup or a new demo using Avatar component that achieves the above expected result? 😄 @eps1lon

I would like to work on this feature, if possible.