Added arch detection to kubectl download

[gtrubach]

This PR adds the arch detection to kubectl download using os.arch() call. It won't work on all arch's, but should support amd64, arm and arm64 on Linux (and some more - https://kubernetes.io/docs/setup/release/notes/#client-binaries). If the action is run on non-supported arch by kubectl it won't be able to download and will fail.

Should fix #115.

[ghost]

All CLA requirements met.

[gtrubach]

Integration tests seems to be failing because of ${{ secrets.L2_REPO_TOKEN }} missing.

[gtrubach]

To test it I created another branch in my fork kubectl-multiarch-test where I checked-in node_modules. Then I created a repo to test this here https://github.com/gtrubach/k8s-deploy-test which points to the action in that branch and tries to deploy to my local cluster.

The result is here - https://github.com/gtrubach/k8s-deploy-test/runs/1999747697. It uses two self-hosted runners: Windows X64 and Raspberry Pi 2 ARM. Both successful.

Please let me know if anything is needed to be fixed.

[thesattiraju]

Paging @gtrubach to address the comments, so we can take this forward 😄

[thesattiraju]

@gtrubach one last thing left, before I merge. You have to update/add the unit test. You can find the failing test here: https://github.com/Azure/k8s-deploy/pull/117/checks?check_run_id=2088920179

[gtrubach]

@DS-MS - Sorry, my bad. I saw the tests failed but was confused with the red error message about token.

I extended that test to run with several test cases and added another test to test that we handle 404 cases.