[YANG] Add trap flow counter to yang model (#9353)

*[YANG] Add trap flow counter to yang model

src/sonic-yang-models/tests/yang_model_tests/tests_config/flex_counter.json

@@ -34,6 +34,9 @@
                 },
                 "ACL": {
                     "FLEX_COUNTER_STATUS": "enable"
+                },
+                "FLOW_CNT_TRAP": {
+                    "FLEX_COUNTER_STATUS": "enable"
                 }
             }
         }

src/sonic-yang-models/yang-models/sonic-flex_counter.yang

@@ -161,6 +161,16 @@ module sonic-flex_counter {
                 }
             }
 
+            container FLOW_CNT_TRAP {
+                /* HOSTIF_TRAP_COUNTER_FLEX_COUNTER_GROUP */
+                leaf FLEX_COUNTER_STATUS {
+                    type flex_status;
+                }
+                leaf FLEX_COUNTER_DELAY_STATUS {
+                    type flex_delay_status;
+                }
+            }
+
         }
         /* end of container FLEX_COUNTER_TABLE */
     }