[native] introduce user profile component

Summary:
This diff introduces the barebones UserProfile component. Right now we only have the user avatar and the username, but in subsequent diffs we will be adding to this component with the various other parts needed for the profile.

Here is what the designs look like:

Depends on D8914

Test Plan:
Please see screenshot below

Reviewers: atul, inka

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8914