[keyserver] Use correct font for Comm title

Summary:
Get fonts url, link it to the page and use in a header.

Depends on D7312

Test Plan: Check if the font is used. Inspect web debugger and check if the fonts file is fetched.

Reviewers: bartek, kamil

Reviewed By: kamil

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D7330