Set pre-step status to skipped if job is skipped (go-gitea#29489)

close go-gitea#27496
1. Set pre-step (Set up job) status to `skipped` if job is skipped.
2. Apart from pre-step, the other steps should also be set to `skipped`.
The status of other steps are reported from the runner side. This will
be completed by this PR: https://gitea.com/gitea/act_runner/pulls/500

before:

![image](https://github.com/go-gitea/gitea/assets/33891828/4bac2ba9-66de-4679-b7ed-fbae459c0c54)

after:

![image](https://github.com/go-gitea/gitea/assets/33891828/ead4871a-4e0f-4bb1-9fb4-37f4fdb78dfc)

modules/actions/task_state.go

@@ -35,6 +35,9 @@ func FullSteps(task *actions_model.ActionTask) []*actions_model.ActionTaskStep {
 	} else if task.Status.IsDone() {
 		preStep.Stopped = task.Stopped
 		preStep.Status = actions_model.StatusFailure
+		if task.Status.IsSkipped() {
+			preStep.Status = actions_model.StatusSkipped
+		}
 	}
 	logIndex += preStep.LogLength