Summary:
Currently, usage is only shown for free team sites, and only
for total number of rows used in a document. Future diffs will
include other usage metrics and browser tests.
Test Plan: Planned for future diffs; UI is still under development.
Reviewers: jarek
Reviewed By: jarek
Subscribers: alexmojaki
Differential Revision: https://phab.getgrist.com/D3343
