fix: treat empty ps restart-policy as an unset

`dokku ps:set <app> restart-policy` with no value erroneously returned `Invalid restart-policy specified` instead of unsetting the property like every other ps property. The restart policy is now managed as a normal app and global property surfaced through the `--ps-restart-policy`, `--ps-global-restart-policy`, and `--ps-computed-restart-policy` report flags, with the effective value applied at deploy time and existing values migrated on install. Because it is no longer stored as a Docker option it no longer appears in `docker-options:report`, and `--ps-restart-policy` now reports the raw value with the `on-failure:10` default available via `--ps-computed-restart-policy`.

plugins/ps/src/triggers/triggers.go

@@ -28,6 +28,9 @@ func main() {
 		appName := flag.Arg(0)
 		sourceWorkDir := flag.Arg(1)
 		err = ps.TriggerCorePostExtract(appName, sourceWorkDir)
+	case "docker-args-process-deploy":
+		appName := flag.Arg(0)
+		err = ps.TriggerDockerArgsProcessDeploy(appName)
 	case "install":
 		err = ps.TriggerInstall()
 	case "post-app-clone":