build: parameterize arch builds

Build zot artifacts for multiple os and arch.
[linux, amd64] - common case
[linux, arm64] - raspberry pi
[darwin, amd64] - Intel-based macs
[darwin, arm64] - Arm-based macs

Signed-off-by: Ramkumar Chinchani <rchincha@cisco.com>

Dockerfile-zxp

@@ -2,10 +2,13 @@
 # Stage 1: Build binary, create default config file
 # ---
 FROM ghcr.io/project-zot/golang:1.17 AS builder
+ARG COMMIT
+ARG OS
+ARG ARCH
 RUN mkdir -p /go/src/github.com/project-zot/zot
 WORKDIR /go/src/github.com/project-zot/zot
 COPY . .
-RUN make clean exporter-minimal
+RUN make COMMIT=$COMMIT OS=$OS ARCH=$ARCH clean exporter-minimal
 RUN echo '{\n\
     "Server": {\n\
         "protocol": "http",\n\
@@ -24,7 +27,7 @@ RUN echo '{\n\
 # Stage 2: Final image with nothing but binary and default config file
 # ---
 FROM scratch AS final
-COPY --from=builder /go/src/github.com/project-zot/zot/bin/zxp /zxp
+COPY --from=builder /go/src/github.com/project-zot/zot/bin/zxp-$OS-$ARCH /zxp
 COPY --from=builder /go/src/github.com/project-zot/zot/config.json /etc/zxp/config.json
 ENTRYPOINT ["/zxp"]
 EXPOSE 5001