docker: reduce images size for client as well

By introducing multi-stage build
And switching to alpine
And using grpcurl from docker

x10 size reduction !

```
$ docker images | grep opi
opi-storage-client                      main           cd27f72378fb   2 minutes ago       20.4MB
ghcr.io/opiproject/opi-storage-client   main           633e8f737c1a   18 hours ago        612MB

```

Signed-off-by: Boris Glimcher <Boris.Glimcher@emc.com>

client/Dockerfile

@@ -1,8 +1,7 @@
-# syntax=docker/dockerfile:1
+# SPDX-License-Identifier: Apache-2.0
+# Copyright (c) 2022 Dell Inc, or its subsidiaries.
 
-# Alpine is chosen for its small footprint
-# compared to Ubuntu
-FROM docker.io/library/golang:1.19.5-alpine
+FROM docker.io/library/golang:1.19.5-alpine as builder
 
 WORKDIR /app
 
@@ -15,5 +14,8 @@ RUN go mod download
 COPY *.go ./
 RUN go build -v -o /opi-storage-client && CGO_ENABLED=0 go test -v ./...
 
+# second stage to reduce image size
+FROM alpine:3.17
+COPY --from=builder /opi-storage-client /
 EXPOSE 50051
-CMD [ "/opi-storage-client" ]
+CMD [ "/opi-storage-client"]