[native] extend avatar component to handle images

Summary:
Extended avatar component to either render an emoji avatar or image avatar depending on avatarInfo.type.

Since Multimedia only uses type and uri from mediaInfo, I only included those fields in the AvatarMediaInfo type.

Depends on D7245

Test Plan:
To test if the image was rendering correctly, I injected the following as the avatarInfo:

const avatarInfo = { type: 'image', uri: 'https://picsum.photos/200' };

Please see the screenshots to see how the image avatar looks for each size:

Profile:

Large:

Small:

Micro:

Reviewers: ashoat, atul, bartek

Reviewed By: atul, bartek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7187