Upgrade: controller-gen v0.5.0, conversion-gen v0.21.0

frameworks/constraint had previously been reliant on an outdated version
of the controller-gen library for generating CRDs with embedded
JSONSchemas.  The older version of the library wasn't built to detect
a nested JSONSchema, and thus would not refuse it.

With the requirement of v1 CRDs around the corner in k8s 1.22,
framework/constraint requires the newer controller-gen v0.5.0.  This
library version can output v1 CRD.

The conversion logic was also in need of a library upgrade, with
conversion-gen v0.21.0 now generating the necessary files.

This PR _does not_ output a v1 CRD for Constraint Template.  That will
be left for a future PR.  This PR brings the two binaries up-to-date.

Note: I attempted to dockerize these two binaries.  Controller-gen
worked fine, but for some reason conversion-gen couldn't write to the
filesystem.  The output looked fine, but no dice.  Rather than figure
out why, I decided to punt on the dockeriziation effort.

Signed-off-by: juliankatz <juliankatz@google.com>

constraint/Makefile

@@ -28,24 +28,30 @@ test: generate
 install: manifests
 	kubectl apply -f config/crds
 
+# Install the generation dependencies on the location machine
+gen-dependencies:
+	GO111MODULE=on go get sigs.k8s.io/controller-tools/cmd/controller-gen@v0.5.0
+	GO111MODULE=on go get k8s.io/code-generator/cmd/conversion-gen@v0.20.2
+
 # Generate manifests e.g. CRD, RBAC etc.
-manifests: buildutils
-	controller-gen all
-	kustomize build config -o deploy/crds.yaml
+manifests:
+	controller-gen \
+		crd:crdVersions="v1beta1",allowDangerousTypes="true" \
+		paths="./pkg/..." \
+		output:crd:artifacts:config=config/crds
+	cp config/crds/* deploy/crds.yaml
 
 lint:
 	golangci-lint -v run ./... --timeout 5m
 
 # Generate code
-generate: buildutils
-ifndef GOPATH
-	$(error GOPATH not defined, please define GOPATH. Run "go help gopath" to learn more about GOPATH)
-endif
-	export GOROOT=$(go env root)
-	GO111MODULE=off go generate ./pkg/...
-
-# find or download controller-gen
-# download controller-gen if necessary
-.PHONY: buildutils
-buildutils:
-	cd buildutils && ./buildutils.sh
+# Not working?  Try running `make gen-dependencies`
+generate:
+	controller-gen \
+		object:headerFile=./hack/boilerplate.go.txt \
+		paths="./pkg/..."
+	conversion-gen \
+		--input-dirs "./pkg/apis/templates/..." \
+		--go-header-file=./hack/boilerplate.go.txt \
+		--output-file-base=zz_generated.conversion \
+		--extra-peer-dirs=k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1