Bump k0sctl to v0.16.0

[twz123]

Description

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Manual test
• Auto test added

Checklist:

• My code follows the style guidelines of this project
• My commit messages are signed-off
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[kke]

There are quite many places that need to be changed 🤔

[twz123]

There are quite many places that need to be changed 🤔

There could be fewer places.

1. I wonder why tool's go.mod wasn't bumped by dependabot. Maybe we were too impatient?
2. Maybe check-network could eventually become a workflow call to ostests-e2e.
3. Not sure about k0sctl_test.go. Maybe we could just drop that test?
4. The changes to the Alpine files were just the removal of workarounds for v0.15.5. Changing those files won't be required in the future, hopefully.