venconn: add integration tests using envtest

Note that I should probably have gone with a fake of the
ConnectionHandler instead of an envtest. We will move to the fake later
on.

I added the venaficonnection CRDs manually for now. I have a PR to
automate pulling these CRDs from the venafi-connection-lib project:
#556

For now, I added these manifests manually with the following commands:

  gh pr checkout 556
  git checkout -
  git checkout step1-makefile-modules -- deploy/charts/venafi-kubernetes-agent/templates/venafi-connection-crd{,.without-validations}.yaml

.gitignore

@@ -13,3 +13,4 @@ predicate.json
 *.pub
 *.tgz
 
+_bin

Makefile

@@ -48,7 +48,8 @@ build:
 install:
 	cd $(ROOT_DIR) && $(GO_INSTALL)
 
-test:
+export KUBEBUILDER_ASSETS=$(ROOT_DIR)/_bin/tools
+test: _bin/tools/etcd _bin/tools/kube-apiserver
 	cd $(ROOT_DIR) && go test ./...
 
 vet: