Add option to exclude packages introduced from a base layer

What would you like to be added:

further options on the scope flag.

Why is this needed:

First, I am not sure if I properly understood. When we speak about layer, do we speak about container layers, e.g. from docker?
If yes, I wish I could scan only the components of the 'latest' / 'top' layer of my docker images.

Indeed, in our team, I built a hierarchy of docker images, where the Dockerfile already start with

FROM {someBaseImage}

so that I share a common 'debian-base' as 'lowest' layer on all my images.

Currently, the Debian packages are duplicated in all the SBOM of all images.
I wish I could avoid this duplication.

A possible workaround is a postprocessing script filtering out components by their layerId, but it is a bit tricky to find out which layerId I want to keep!

Skipping completely the Debian registery is not a clean workaround since I might have a Debian package installed only on my 'top layer'.

Possible related issue: https://github.com/anchore/syft/issues/435

Start with the scope flag and the related discussion in issue #435, then verify how Docker base and top layers are represented in generated SBOMs. Done means an option can exclude packages inherited from a base layer while retaining packages installed on the selected top layer, without relying on manual layerId postprocessing.