go/svc: finish porting services to Bazel

The following services were never ported:
 - cmc-proxy
 - arista-proxy
 - m6220-proxy
 - topo

They now build.

Change-Id: I0688bfe43cdff946e6662e21969ef539382c0e86
diff --git a/go/svc/m6220-proxy/proto/proxy.proto b/go/svc/m6220-proxy/proto/proxy.proto
new file mode 100644
index 0000000..bc840ad
--- /dev/null
+++ b/go/svc/m6220-proxy/proto/proxy.proto
@@ -0,0 +1,16 @@
+syntax = "proto3";
+package proto;
+option go_package = "code.hackerspace.pl/hscloud/go/svc/m6220-proxy/proto";
+
+message RunCommandRequest {
+    string command = 1;
+};
+
+message RunCommandResponse {
+    string effective_command = 1;
+    repeated string lines = 2;
+};
+
+service M6220Proxy {
+    rpc RunCommand(RunCommandRequest) returns (RunCommandResponse);
+};