Expose epic counts via GraphQL
Summary
With #268372 (closed), we're implementing Epics list in Vue using issuable_list
app (which is also in use for Test Case and Jira issues), and it involves rendering of tabs happen via Vue;
In !46769 (merged), we're currently relying on issuables_count_for_state
helper to provide counts to show on those tabs, but a better long term approach is to have this count too provided via GraphQL.