[web] introduce XL and XXL sizes to the avatar component

Summary:
When building the user profiles on native we needed to introduce two new size variants: XL and XXL for our avatar component. We will need these two new variants for the avatar on the user profile and the avatar for the full screen view.

Since one of the newly introduced variants (100x100) is going to be smaller than the current L size (112x112), the current L size will now be "XL".

L => 100x100
XL => 112x112
XXL => 480x480

Depends on D9407

Test Plan:
Please see screenshots below

L (100x100):

XL (112x112):

XXL (480x480):

Reviewers: atul, inka

Reviewed By: atul

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9408