Add echo image to avoid building and installing dependencies in each test (#5028)

images/echo/Makefile

@@ -0,0 +1,33 @@
+# Copyright 2020 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Docker image for e2e testing.
+
+# Use the 0.0 tag for testing, it shouldn't clobber any release builds
+TAG ?= 0.0
+
+REGISTRY ?= ingress-controller
+DOCKER ?= docker
+
+IMGNAME = echo
+IMAGE = $(REGISTRY)/$(IMGNAME)
+
+container:
+	$(DOCKER) buildx build \
+		--load \
+		--platform linux/amd64 \
+		-t $(IMAGE):$(TAG) .
+
+clean:
+	$(DOCKER) rmi -f $(IMAGE):$(TAG) || true