Add command for uploading file to SUBNET issue (#4854)

mc support upload --issue <issueNum> --comment <msg> <alias> </path/to/file>

Will upload the given file to the given SUBNET issue

cmd/support.go

@@ -55,6 +55,7 @@ var supportSubcommands = []cli.Command{
 	supportProfileCmd,
 	supportTopCmd,
 	supportProxyCmd,
+	supportUploadCmd,
 }
 
 var supportCmd = cli.Command{