Add k3d-helm build image

buildimages/k3d-helm/Dockerfile

+FROM docker:${DOCKER_VERSION:-latest}
+
+RUN apk add -U wget bash openssl
+# install kubectl
+RUN wget -q -O /usr/local/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/${KUBECTL}/bin/linux/amd64/kubectl && \
+    chmod +x /usr/local/bin/kubectl
+# install k3d
+RUN wget -q -O - https://raw.githubusercontent.com/rancher/k3d/main/install.sh | bash
+# install Helm
+RUN wget -q -O - https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 | bash