build: move e2e dependencies into e2e/go.mod

Several packages are only used while running the e2e suite. These
packages are less important to update, as the they can not influence the
final executable that is part of the Ceph-CSI container-image.

By moving these dependencies out of the main Ceph-CSI go.mod, it is
easier to identify if a reported CVE affects Ceph-CSI, or only the
testing (like most of the Kubernetes CVEs).

Signed-off-by: Niels de Vos <ndevos@ibm.com>

e2e/vendor/k8s.io/kubernetes/pkg/util/slice/slice.go

@@ -0,0 +1,75 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package slice provides utility methods for common operations on slices.
+package slice
+
+import (
+	"sort"
+)
+
+// CopyStrings copies the contents of the specified string slice
+// into a new slice.
+func CopyStrings(s []string) []string {
+	if s == nil {
+		return nil
+	}
+	c := make([]string, len(s))
+	copy(c, s)
+	return c
+}
+
+// SortStrings sorts the specified string slice in place. It returns the same
+// slice that was provided in order to facilitate method chaining.
+func SortStrings(s []string) []string {
+	sort.Strings(s)
+	return s
+}
+
+// ContainsString checks if a given slice of strings contains the provided string.
+// If a modifier func is provided, it is called with the slice item before the comparation.
+func ContainsString(slice []string, s string, modifier func(s string) string) bool {
+	for _, item := range slice {
+		if item == s {
+			return true
+		}
+		if modifier != nil && modifier(item) == s {
+			return true
+		}
+	}
+	return false
+}
+
+// RemoveString returns a newly created []string that contains all items from slice that
+// are not equal to s and modifier(s) in case modifier func is provided.
+func RemoveString(slice []string, s string, modifier func(s string) string) []string {
+	newSlice := make([]string, 0)
+	for _, item := range slice {
+		if item == s {
+			continue
+		}
+		if modifier != nil && modifier(item) == s {
+			continue
+		}
+		newSlice = append(newSlice, item)
+	}
+	if len(newSlice) == 0 {
+		// Sanitize for unit tests so we don't need to distinguish empty array
+		// and nil.
+		newSlice = nil
+	}
+	return newSlice
+}