feat(misconf): add support of buildkit instructions when building dockerfile from image config

[DmitriyLewen]

Description

Buildkit has different format for COPY, ADD and RUN commands:

➜ cat Dockerfile 
FROM alpine

ADD ./foo.txt /foo.txt
COPY ./foo /foo
RUN ls -hl /foo
USER foo
HEALTHCHECK --interval=10s --timeout=3s --retries=0 CMD curl -sS 127.0.0.1 || exit 1%   

➜ docker image history 5989
IMAGE          CREATED             CREATED BY                                      SIZE      COMMENT
19c56c9f1c3c   About an hour ago   HEALTHCHECK &{["CMD-SHELL" "curl -sS 127.0.0…   0B        buildkit.dockerfile.v0
<missing>      About an hour ago   USER foo                                        0B        buildkit.dockerfile.v0
<missing>      About an hour ago   RUN /bin/sh -c ls -hl /foo # buildkit           0B        buildkit.dockerfile.v0
<missing>      About an hour ago   COPY ./foo /foo # buildkit                      3B        buildkit.dockerfile.v0
<missing>      About an hour ago   ADD ./foo.txt /foo.txt # buildkit               3B        buildkit.dockerfile.v0
<missing>      7 months ago        /bin/sh -c #(nop)  CMD ["/bin/sh"]              0B        
<missing>      7 months ago        /bin/sh -c #(nop) ADD file:289c2fac17119508c…   7.66MB  

We need to add support for these formats when decoding image config into the dockerfile to detect incorrect configurations.

Related issues

• Close feat(image): Buildkit support for misconfiguration scanning #5989

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).