chore: return with an exit code of 1 on supplying an unknown command

Author: jamesgeorge007

packages/@vue/cli/bin/vue.js

@@ -224,6 +224,7 @@ program
     console.log(`  ` + chalk.red(`Unknown command ${chalk.yellow(cmd)}.`))
     console.log()
     suggestCommands(cmd)
+    process.exitCode = 1
   })
 
 // add some useful info on help