e2e: accept context from Ginkgo

Every ginkgo callback should return immediately when a timeout occurs or the
test run manually gets aborted with CTRL-C. To do that, they must take a ctx
parameter and pass it through to all code which might block.

This is a first automated step towards that: the additional parameter got added
with

    sed -i 's/\(framework.ConformanceIt\|ginkgo.It\)\(.*\)func() {$/\1\2func(ctx context.Context) {/' \
        $(git grep -l -e framework.ConformanceIt -e ginkgo.It )
    $GOPATH/bin/goimports -w $(git status | grep modified: | sed -e 's/.* //')

log_test.go was left unchanged.

test/e2e/windows/device_plugin.go

@@ -50,7 +50,7 @@ var _ = SIGDescribe("[Feature:GPUDevicePlugin] Device Plugin", func() {
 		e2eskipper.SkipUnlessNodeOSDistroIs("windows")
 		cs = f.ClientSet
 	})
-	ginkgo.It("should be able to create a functioning device plugin for Windows", func() {
+	ginkgo.It("should be able to create a functioning device plugin for Windows", func(ctx context.Context) {
 		ginkgo.By("creating Windows device plugin daemonset")
 		dsName := "directx-device-plugin"
 		daemonsetNameLabel := "daemonset-name"