Support changing labels of Actions runner without re-registration (#24806)

close #24540

related:
- Protocol: https://gitea.com/gitea/actions-proto-def/pulls/9
- Runner side: https://gitea.com/gitea/act_runner/pulls/201

changes:
- Add column of `labels` to table `action_runner`, and combine the value
of `agent_labels` and `custom_labels` column to `labels` column.
- Store `labels` when registering `act_runner`.
- Update `labels` when `act_runner` starting and calling `Declare`.
- Users cannot modify the `custom labels` in edit page any more.

other changes:
- Store `version` when registering `act_runner`.
- If runner is latest version, parse version from `Declare`. But older
version runner still parse version from request header.

models/actions/task.go

@@ -241,11 +241,9 @@ func CreateTaskForRunner(ctx context.Context, runner *ActionRunner) (*ActionTask
 
 	// TODO: a more efficient way to filter labels
 	var job *ActionRunJob
-	labels := runner.AgentLabels
-	labels = append(labels, runner.CustomLabels...)
-	log.Trace("runner labels: %v", labels)
+	log.Trace("runner labels: %v", runner.AgentLabels)
 	for _, v := range jobs {
-		if isSubset(labels, v.RunsOn) {
+		if isSubset(runner.AgentLabels, v.RunsOn) {
 			job = v
 			break
 		}