Move and fix GetContainerRuntime check from bpfd proc

[MyIgel]

Fixes #1592 (again)

Description
This adds a slimmed down version of https://github.com/genuinetools/bpfd/blob/a4bfa5e3e9d1bfdbc56268a36a0714911ae9b6bf/proc/proc.go as the original package is unmaintained (~3y no updates of its 0.0.1 release) and kaniko only needs the container runtime detection, see #1686 (comment) . To fix the problem, it has #1686 already applied to it.

The alternative to this change would be to rebuild this functionality, but I'm not totally sure if I could do that by my own due to a lack of go experience but I could try if it would be better to have a "kaniko implementation" of the functionality.

Submitter Checklist

• Includes unit tests (at least the original ones)
• Adds integration tests if needed. (nope)

Reviewer Notes

• The code flow looks good.
• Unit tests and/or integration tests added.

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[imjasonh]

Boilerplate missing in:
././pkg/util/proc_test.go
././pkg/util/proc.go

Please add the boilerplate text to the top of these new files.

Also, could we maybe move them into pkg/util/proc? Having a single huge util package with so much different functionality in it is kind of a smell. I'd like to clean that up in general in the future, and this would be a good step.

[MyIgel]

I can definitely move it but wouldn't adding the boilerplate mean that it gets relicensed? I mean I actually don't think that this would be an issue as its MIT to Apache 2 and not an substantial part of the code with a relevantly complex software part but whats your opinion here @imjasonh?

[MyIgel]

I added the boilerplate and did some more cleanup, that should be sufficient i guess :D