Make kaniko abort when pkg/filesystem/resolve.go ResolvePaths() found…

[santiagorr]

Description

Make kaniko abort when pkg/filesystem/resolve.go ResolvePaths() founds a symlink target that doesn't exist

Fixes #2709

Submitter Checklist

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• Includes unit tests
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Reviewer Notes

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

Release Notes

Describe any changes here so maintainer can include it in the release notes, or delete this block.

Examples of user facing changes:
- kaniko adds a new flag `--registry-repo` to override registry

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