S2 AvatarGroup (#6781)
* Add Spectrum 2 docs to storybook
* add avatar group
* lint
* updates
* feedback updates
* more feedback changes
* properly forward ref and add aria label interface
* Move stroke to Avatar and switch to pixel-based sizing
* Fix TS
* Add support for aria labeling
---------
Co-authored-by: Jeff Luyau <luyau@adobe.com>
Co-authored-by: Robert Snow <rsnow@adobe.com>
Co-authored-by: Yihui Liao <44729383+yihuiliao@users.noreply.github.com>
Co-authored-by: Kyle Taborski <ktabors@yahoo.com>
