When having not square images for user avatar several issues appear
* website_slides: heroes of the week banner is broken as circles are not
circles anymore. They look more like UFOs or funny snowmen;
* website_slides: my user status / leaderboard / achievements card display
is broken as image may take much more width than planned;
* website_slides: channel page view displays user avatar when having joined
it, and it is broken;
* website_profile: user avatars in top 3 of users karma ranking is broken.
In this commit we apply strict rules on width / height combined to an object
fit in order to always have a bioutifoul displayed circled image.
Task 2065425 (avatar ratio badly displayed)
PR #36756
Thibault Delavallée
98f847be3a