implement kubectl-apply module

[sharabiani]

Kubectl-apply module implemented:

It supports:

• String manifest body
• Local files
• Local template files
• URLs
• Directories containing yaml and template files

gke-cluster updated and pre-existing-gke-cluster updated:

• To replace kubectl provider with kubectl-apply module to apply create newtrok objects for multinetworking
• To template files as manifests instead of raw content

The template files in gke-cluster and pre-existing-gke-cluster are added to duplicate diff

Submission Checklist

Please take the following actions before submitting this pull request.

• Fork your PR branch from the Toolkit "develop" branch (not main)
• Test all changes with pre-commit in a local branch #
• Confirm that "make tests" passes all tests
• Add or modify unit tests to cover code changes
• Ensure that unit test coverage remains above 80%
• Update all applicable documentation
• Follow Cluster Toolkit Contribution guidelines #