[landing] introduce differenation section

Summary:
This diff introduces the new differentiation section on the landing page. Since the copy for this section is not ready atm, I gated this section behind a flag that can easily be enabled/disabled when ready

Depends on D12630

Test Plan:
Please see the demo video below

Reviewers: ashoat, inka

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12631