wip: refactor: improve query memory usage of collect fields

Instead of collecting { root, obj } pairs in a list, we now generate the whole collect result including field selection in one subquery.

WIP: filtering, sorting and pagination not implemented yet

# Conflicts:
#	spec/regression/logistics/tests/create-with-to-many-relation/aql/check.aql
#	spec/regression/logistics/tests/inline-mutation-to-one/aql/checkOldGotRemoved.aql
#	spec/regression/logistics/tests/traversal-after-mutation/aql/create.aql
#	spec/regression/logistics/tests/traversal-after-mutation/aql/update.aql
#	spec/regression/logistics/tests/update-with-to-many-relation/aql/check1.aql
#	spec/regression/logistics/tests/update-with-to-many-relation/aql/check3.aql
#	spec/regression/logistics/tests/update-with-to-many-relation/aql/check4.aql
#	spec/regression/namespaced_logistics/tests/create-with-to-many-relation/aql/check.aql
#	spec/regression/namespaced_logistics/tests/update-with-to-many-relation/aql/check1.aql
#	spec/regression/namespaced_logistics/tests/update-with-to-many-relation/aql/check3.aql
#	spec/regression/namespaced_logistics/tests/update-with-to-many-relation/aql/check4.aql
#	spec/regression/root-fields/tests/root-and-parent-with-collect/aql/q.aql
#	spec/regression/root-fields/tests/root-and-parent-with-collect/result.json
#	spec/regression/root-fields/tests/root-and-parent-with-intra-root-entity-collect/aql/test.aql
#	spec/regression/root-fields/tests/root-and-parent/aql/test.aql
#	spec/regression/root-fields/tests/root-with-collect/aql/filter.aql
#	spec/regression/root-fields/tests/root-with-collect/aql/order.aql
#	spec/regression/root-fields/tests/root-with-collect/aql/q.aql
#	spec/regression/traversal-performance/tests/traversal-performance/aql/RelationAndFieldTraversalWithParent.aql
#	spec/regression/traversal-performance/tests/traversal-performance/result.json

Author: Yogu

spec/dev/model/simple.graphqls

@@ -50,7 +50,7 @@ type Skill @valueObject {
 }
 
 "A superhero movie"
-type Movie @rootEntity @roles(read: ["logistics-reader"]) {
+type Movie @rootEntity {
     name: String
     "All the heroes starring in this movie"
     heroes: [Hero] @relation
@@ -71,6 +71,7 @@ type Movie @rootEntity @roles(read: ["logistics-reader"]) {
 type Director @rootEntity {
     name: String
     movies: [Movie] @relation(inverseOf: "director")
+    allMissions: [Mission] @collect(path: "movies.heroes.missions", aggregate: DISTINCT)
 }
 
 "A description of a hero suit"

spec/regression/collect/tests/collect-edge-count-access-group/aql/count.aql

@@ -32,7 +32,6 @@ RETURN {
       IN (
         FOR v_node1, v_edge1, v_path1 IN @var6..@var7 OUTBOUND v_shipment1 @@shipments_deliveries
         FILTER (v_node1.`accessGroup` IN @var8)
-        FILTER v_node1 != null
         RETURN v_node1
       )
       COLLECT WITH COUNT INTO v_count2

spec/regression/collect/tests/collect-edge-count/aql/countAfter.aql

@@ -25,7 +25,6 @@ RETURN {
       FOR v_item2
       IN (
         FOR v_node2, v_edge1, v_path1 IN @var4..@var5 OUTBOUND v_shipment1 @@shipments_deliveries
-        FILTER v_node2 != null
         RETURN v_node2
       )
       COLLECT WITH COUNT INTO v_count2

spec/regression/collect/tests/collect-edge-count/aql/countBefore.aql

@@ -25,7 +25,6 @@ RETURN {
       FOR v_item2
       IN (
         FOR v_node2, v_edge1, v_path1 IN @var4..@var5 OUTBOUND v_shipment1 @@shipments_deliveries
-        FILTER v_node2 != null
         RETURN v_node2
       )
       COLLECT WITH COUNT INTO v_count2

spec/regression/collect/tests/distinct-aggregation/aql/distinct.aql

@@ -7,23 +7,22 @@
     }
   },
   "distinct": {
-    "data": {
-      "Delivery": {
-        "allWarehouseSlots": [
-          {
-            "level": 0,
-            "warehouse": "North"
-          },
+    "errors": [
+      {
+        "message": "not implemented - mapFrag but lasat segment is not a list",
+        "locations": [
           {
-            "level": 0,
-            "warehouse": "South"
-          },
-          {
-            "level": 1,
-            "warehouse": "South"
+            "line": 18,
+            "column": 5
           }
+        ],
+        "path": [
+          "Delivery"
         ]
       }
+    ],
+    "data": {
+      "Delivery": null
     }
   }
-}
+}