feat: add containerimage support, solve #1734

[bncmajor]

Fixes #1734

Description

Currently Kaniko does not support .containerignore files and the change solves it by mimicing Podman behavior in this case. (if .containerignore present that's used, otherwise .dockerignore used)

Submitter Checklist

• [x] Includes unit tests
• [x] Adds integration tests if needed.

Reviewer Notes

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

Release Notes

• kaniko adds support for .containerignore as primary ignore file

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[bncmajor]

@JeromeJu @QuanZhang-William could any of you have a look at this?