feat: avoid importing kubectl deps when using ApplysetApplier

[yuwenma]

What this PR does / why we need it: This PR allows k-d-p operators to not import the kubectl dependent libraries if using ApplysetApplier.

CI change and test coverage: Some Test files are tagged with without_kubectl_deps specifically. We added a new CI test run in the dev/test to make sure those tests are run with the without_kubectl_deps tag

CGO_ENABLED=0 go test -tags without_kubectl_deps -count=1 -v ./...

usage:

Take Guestbook as an example,

// examples/guestbook-operator/controllers/guestbook_controller.go
applier := applier.NewApplySetApplier(metav1.PatchOptions{}, metav1.DeleteOptions{}, applier.ApplysetOptions{})
return r.Reconciler.Init(mgr, &api.Guestbook{},
        ...
        declarative.WithApplier(applier),
        declarative.WithApplyPrune())

go run -tags without_kubectl_deps main.go

[yuwenma]

/assign @justinsb

[yuwenma]

Looks good, but I think if we can avoid go:build without_kubectl_deps except in one file that builds the default object, I think this PR gets simpler.

qq: but I think this will cause the without_kubectl_deps test to call the test cases that need the kubectl dep (which cause undefined error because the direct.go and exec.go are excluded). e.g. run go test -tags without_direct_applier,without_exec_applier will include test with_kubectl_test.go:

// assuming I commented out the tags
//go:build !without_exec_applier || !without_direct_applier
// +build !without_exec_applier !without_direct_applier

func TestSimpleReconciler(t *testing.T) {
    Key := "direct"
    t.Run(Key, func(t *testing.T) {
        testharness.RunGoldenTests(t, "testdata/reconcile/"+Key+"/", func(h *testharness.Harness, testdir string) {
            // ! NewDirectApplier raises undeclared error
            testSimpleReconciler(h, testdir, applier.NewDirectApplier(), status.NewBasic(nil)) 
        })
    })
}

[justinsb]

Thanks @yuwenma - lgtm!

/approve /lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: justinsb, yuwenma

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