Audit and enable HTTP/2 push

In #14952 (closed) we plan to enable HTTP/2, but we are postponing enabling HTTP/2 push in case there are potential privacy concerns. Let's investigate any concerns here and hopefully enable push in the future.

Edited Aug 05, 2022 by Pier Angelo Vendrame

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information