refactor: unify command declaration across codebase

plugins/ps/subcommands/start

@@ -6,9 +6,12 @@ source "$PLUGIN_AVAILABLE_PATH/ps/functions"
 
 cmd-ps-start() {
   declare desc="starts app via command line"
-  local cmd="ps:start"
-  [[ -z $2 ]] && dokku_log_fail "Please specify an app to run the command on"
-  ps_start "$2"
+  declare cmd="ps:start"
+  [[ "$1" == "$cmd" ]] && shift 1
+  declare APP="$1"
+
+  [[ -z "$APP" ]] && dokku_log_fail "Please specify an app to run the command on"
+  ps_start "$APP"
 }
 
 cmd-ps-start "$@"