[Feature][Core] Add PendingJobs info in the response of GetOverviewOperation

docs/en/seatunnel-engine/rest-api-v2.md

@@ -60,6 +60,7 @@ Please refer [security](security.md)
     "unassignedSlot":"0",
     "works":"1",
     "runningJobs":"0",
+    "pendingJobs":"0",
     "finishedJobs":"0",
     "failedJobs":"0",
     "cancelledJobs":"0"

docs/zh/seatunnel-engine/rest-api-v2.md

@@ -58,6 +58,7 @@ seatunnel:
     "unassignedSlot":"0",
     "works":"1",
     "runningJobs":"0",
+    "pendingJobs":"0",
     "finishedJobs":"0",
     "failedJobs":"0",
     "cancelledJobs":"0"

seatunnel-e2e/seatunnel-engine-e2e/connector-seatunnel-e2e-base/src/test/java/org/apache/seatunnel/engine/e2e/RestApiIT.java

@@ -667,7 +667,8 @@ public void testOverview() {
                                                 .statusCode(200)
                                                 .body("projectVersion", notNullValue())
                                                 .body("totalSlot", equalTo("40"))
-                                                .body("workers", equalTo("2"));
+                                                .body("workers", equalTo("2"))
+                                                .body("pendingJobs", notNullValue());
                                         given().get(
                                                         HOST
                                                                 + value
@@ -680,7 +681,8 @@ public void testOverview() {
                                                 .statusCode(200)
                                                 .body("projectVersion", notNullValue())
                                                 .body("totalSlot", equalTo("40"))
-                                                .body("workers", equalTo("2"));
+                                                .body("workers", equalTo("2"))
+                                                .body("pendingJobs", notNullValue());
                                     });
                         });
     }

seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/CoordinatorService.java

@@ -1074,6 +1074,10 @@ public ConnectorPackageService getConnectorPackageService() {
         return connectorPackageService;
     }
 
+    public int getPendingJobCount() {
+        return pendingJobQueue.getJobIdMap().size();
+    }
+
     @VisibleForTesting
     protected IMap<Long, HashMap<TaskLocation, SeaTunnelMetricsContext>> getMetricsImap() {
         return metricsImap;

seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/resourcemanager/opeartion/GetOverviewOperation.java

@@ -115,6 +115,7 @@ public static OverviewInfo getOverviewInfo(
                                                 .name()
                                                 .equals(JobStatus.FINISHED.toString()))
                         .count());
+        overviewInfo.setPendingJobs(server.getCoordinatorService().getPendingJobCount());
 
         return overviewInfo;
     }

seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/resourcemanager/resource/OverviewInfo.java

@@ -30,6 +30,7 @@ public class OverviewInfo implements Serializable {
     private long runningJobs;
     private long finishedJobs;
     private long failedJobs;
+    private long pendingJobs;
     private long cancelledJobs;
     private int workers;
 }