sync FT.AGGREGATE (#815)

* sync FT.AGGREGATE

* update command definition and generate the code

* Maintain struct consistency

Author: arbha1erao

Diff for: hack/cmds/commands_search.json

@@ -1203,6 +1203,12 @@
           "VERBATIM"
         ]
       },
+      {
+        "name": "scorer",
+        "type": "string",
+        "optional": true,
+        "command": "SCORER"
+      },
       {
         "name": "timeout",
         "type": "integer",
@@ -1241,6 +1247,24 @@
               }
             ]
           },
+          {
+            "name": "apply",
+            "type": "block",
+            "optional": true,
+            "multiple": true,
+            "block": [
+              {
+                "name": "expression",
+                "type": "string",
+                "command": "APPLY"
+              },
+              {
+                "name": "name",
+                "type": "string",
+                "command": "AS"
+              }
+            ]
+          },
           {
             "name": "groupby",
             "type": "block",
@@ -1351,24 +1375,6 @@
               }
             ]
           },
-          {
-            "name": "apply",
-            "type": "block",
-            "optional": true,
-            "multiple": true,
-            "block": [
-              {
-                "name": "expression",
-                "type": "string",
-                "command": "APPLY"
-              },
-              {
-                "name": "name",
-                "type": "string",
-                "command": "AS"
-              }
-            ]
-          },
           {
             "name": "limit",
             "type": "block",