fix: copy Umask function and remove private package k8s.io/kubernetes/pkg/kubectl/util

[weixiao-huang]

Description of the change:

• Copy Umask function from https://github.com/kubernetes/kubernetes/blob/v1.15.4/pkg/kubectl/util/umask.go
• Remove imported package "k8s.io/kubernetes/pkg/kubectl/util"

Motivation for the change:

"k8s.io/kubernetes/pkg/kubectl/util" has been imported from pkg/ansible/proxy/kubectl.go. However, due to https://github.com/kubernetes/kubernetes/blob/v1.15.4/pkg/kubectl/util/BUILD, this go_library has been declared as a private package only visible inner kubernetes. So if we use bazel in operator-sdk by ourself, this will lead to an error

in go_library rule @com_github_operator_framework_operator_sdk//pkg/ansible/proxy:go_default_library: target '@io_k8s_kubernetes//pkg/kubectl/util:go_default_library' is not visible from target '@com_github_operator_framework_operator_sdk//pkg/ansible/proxy:go_default_library'. Check the visibility declaration of the former target if you think the dependency is legitimate

So we should copy this simple function into out kubectl.go file to avoid this private import

[openshift-ci-robot]

Hi @weixiao-huang. Thanks for your PR.

I'm waiting for a operator-framework member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[estroz]

@weixiao-huang this package restriction is only relevant when using bazel, which the SDK currently does not. If we ever decide to use bazel, we will update our imports to reflect that, copying code if we must. Until then we will import rather than copy code when it makes sense to do so.

[joelanford]

@weixiao-huang As part of the effort to reduce and eventually remove our dependence on k/k, we will be changing this to use k8s.io/kubectl/pkg/util.Umask when we switch to kubernetes 1.16 libraries. See #2145