The setup is explained in the comment, but TL;DR: Use the derivation
hash of static files to create permanent URLs.
Relates to b/151.
Change-Id: Ib1ca3a1a00c90a47f4bf39c29a8b4bbf5b215e7d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3664
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>