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/inconshreveable/mousetrap/README.md

@@ -0,0 +1,23 @@
+# mousetrap
+
+mousetrap is a tiny library that answers a single question.
+
+On a Windows machine, was the process invoked by someone double clicking on
+the executable file while browsing in explorer?
+
+### Motivation
+
+Windows developers unfamiliar with command line tools will often "double-click"
+the executable for a tool. Because most CLI tools print the help and then exit
+when invoked without arguments, this is often very frustrating for those users.
+
+mousetrap provides a way to detect these invocations so that you can provide
+more helpful behavior and instructions on how to run the CLI tool. To see what
+this looks like, both from an organizational and a technical perspective, see
+https://inconshreveable.com/09-09-2014/sweat-the-small-stuff/
+
+### The interface
+
+The library exposes a single interface:
+
+    func StartedByExplorer() (bool)