Add caching to SWH badges views

Feature request from Guix team on IRC:

<c​ivodul> hey! our package browser at https://hpc.guix.info/browse now shows SWH badges
<c​ivodul> i wonder if there could be caching on your side and/or Cache-Control headers on badges
<c​ivodul> at least badges for swh:rev:* can have a pretty much infinite TTL
<c​ivodul> likewise for origin badges

We should cache indefinitely a badge response if the targeted object (origin, directory, ...) can be found in the archive.