Enable Docker BuildKit for chaching dependencies and faster builds

After enabling it with DOCKER_BUILDKIT=1, it allows to use features like caching(--mount=type=cache) and parallel layer execution which increses speed of concurent builds which is great for local development

Dockerfile

@@ -23,7 +23,9 @@ COPY version/ version/
 # was called. For example, if we call make docker-build in a local env which has the Apple Silicon M1 SO
 # the docker BUILDPLATFORM arg will be linux/arm64 when for Apple x86 it will be linux/amd64. Therefore,
 # by leaving it empty we can ensure that the container and binary shipped on it will have the same platform.
-RUN CGO_ENABLED=0 \
+RUN --mount=type=cache,target=/go/pkg/mod \
+    --mount=type=cache,target=/root/.cache/go-build \
+    CGO_ENABLED=0 \
     GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} \
     go build \
     -ldflags "-X \"github.com/1Password/onepassword-operator/version.Version=$operator_version\"" \

Makefile

@@ -132,7 +132,7 @@ run: manifests generate fmt vet ## Run a controller from your host.
 # More info: https://docs.docker.com/develop/develop-images/build_enhancements/
 .PHONY: docker-build
 docker-build: test ## Build docker image with the manager.
-	$(CONTAINER_TOOL) build -t ${IMG} .
+	DOCKER_BUILDKIT=1 $(CONTAINER_TOOL) build -t ${IMG} .
 
 .PHONY: docker-push
 docker-push: ## Push docker image with the manager.