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/github.com/stoewer/go-strcase/snake.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2017, A. Stoewer <adrian.stoewer@rz.ifi.lmu.de>
+// All rights reserved.
+
+package strcase
+
+import (
+	"strings"
+)
+
+// SnakeCase converts a string into snake case.
+func SnakeCase(s string) string {
+	return delimiterCase(s, '_', false)
+}
+
+// UpperSnakeCase converts a string into snake case with capital letters.
+func UpperSnakeCase(s string) string {
+	return delimiterCase(s, '_', true)
+}
+
+// delimiterCase converts a string into snake_case or kebab-case depending on the delimiter passed
+// as second argument. When upperCase is true the result will be UPPER_SNAKE_CASE or UPPER-KEBAB-CASE.
+func delimiterCase(s string, delimiter rune, upperCase bool) string {
+	s = strings.TrimSpace(s)
+	buffer := make([]rune, 0, len(s)+3)
+
+	adjustCase := toLower
+	if upperCase {
+		adjustCase = toUpper
+	}
+
+	var prev rune
+	var curr rune
+	for _, next := range s {
+		if isDelimiter(curr) {
+			if !isDelimiter(prev) {
+				buffer = append(buffer, delimiter)
+			}
+		} else if isUpper(curr) {
+			if isLower(prev) || (isUpper(prev) && isLower(next)) {
+				buffer = append(buffer, delimiter)
+			}
+			buffer = append(buffer, adjustCase(curr))
+		} else if curr != 0 {
+			buffer = append(buffer, adjustCase(curr))
+		}
+		prev = curr
+		curr = next
+	}
+
+	if len(s) > 0 {
+		if isUpper(curr) && isLower(prev) && prev != 0 {
+			buffer = append(buffer, delimiter)
+		}
+		buffer = append(buffer, adjustCase(curr))
+	}
+
+	return string(buffer)
+}