This adds a PathInfoService trait, and an implementation for it using
sled, and one using a HashMap.
Change-Id: I85fe4c9b6105808d7b0c095441326424ffc2d2bb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8099
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
