Scan docker image config metadata

[AlfredBerg]

Description:

This is my attempt at solving #3007 The current implementation only scans the created_by value in the docker image config (https://github.com/opencontainers/image-spec/blob/main/config.md). This misses e.g. the environment variables of the docker image and other fields that commonly contain secrets.

The easiest way to view this metadata is by using "crane config [image]" https://github.com/google/go-containerregistry/tree/main/cmd/crane

Checklist:

• [x] Tests passing (make test-community)? (fails but also fails on main without my changes)
• [x] Lint passing (make lint this requires golangci-lint)?

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