A way to cache the blob-info-cache-v1.sqlite file by nix

[guskovd]

It looks very similar to the fact that nix2container uses a file as a cache between launches
blob-info-cache-v1.sqlite file:

• ~/.local/share/containers/cache/blob-info-cache-v1.sqlite for user
• /var/lib/containers/cache/blob-info-cache-v1.sqlite for root

This behavior seems normal for the skopeo application, but I would like the nix2container application to be able to generate this file itself and store it in /nix/store along with the layers in json format.

This could help a lot in cases where docker images are built in CI