Detect snaps, flatpack, docker images, appimages and assimilated

[pombredanne]

We should also detect as packages the various containerized apps like Flatpak, snaps, and appimages as well as Docker and OCI images (either in a VM, rootfs or in a docker itself)

This is different from the whole image analysis in SCIO. This is instead to find these in a larger codebase scanning context.