[3/n] [landing] add basic teammate profile block with picture, title and social links

Summary:
Add a basic profile block for each team member with their picture, title, and social handles.

Layout, team sections (ex. Team, Team @ SWM), and general layout will be addressed in follow up diffs.

If you patch this diff, you should see this. Again, layout will be addressed in follow up diffs.

Test Plan: render team page.

Reviewers: atul, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, palys-swm, Adrian, karol-bisztyga, boristopalov

Differential Revision: https://phabricator.ashoat.com/D2750