Catalog VM images directly

[wagoodman]

(writing on the behalf of @westonsteimel )

It would be awesome to be able to point syft directly and more filesystem image types:

# search a VMDK disk image
syft ./my.vmdk

# fetch and catalog from an EBS snapshot
syft ami-0abcdef1234567890

(these would also have their own schemes too, such as vmdk and eds)

There are some interesting libs available for accessing EBS images, parsing ext4 filesystems, as well as xfs filesystems.

Ideally we could use the existing stereoscope filetree/index capabilities but have custom syft Source objects to raise specific metadata about that source.