This defines a service that can be used to upload and retrieve metadata
of nix paths.
Change-Id: Id86eb531ce4ae316adb15934b0d1386a14ba2132
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7136
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
