Add build and release for csi proxy to gcs bucket

This PR adds building and publishing csi-proxy binary to gcs bucket k8s-artifacts-csi

Author: jingxu97

build/cloudbuild.yaml

@@ -0,0 +1,19 @@
+# Build the module.
+steps:
+- name: gcr.io/cloud-builders/go:debian
+  entrypoint: bash
+  args:
+  - -c
+  - |
+    set -ex
+    IFS=- read str1 rev <<< "${_GIT_TAG}"
+    make build REV=${rev}
+    cp bin/csi-proxy.exe bin/csi-proxy${_GIT_TAG}.exe
+    echo $_GIT_TAG
+tags: ['jing']
+substitutions:
+  _GIT_TAG: '12345'
+artifacts:
+  objects:
+    location: 'gs://disksize-bucket'
+    paths: 'bin/csi-proxy${_GIT_TAG}.exe'