Add fuzz testing to 'serv' for the GQL hash parser

serv/corpus/001.gql

@@ -0,0 +1,21 @@
+query {
+  products(
+    # returns only 30 items
+    limit: 30,
+
+    # starts from item 10, commented out for now
+    # offset: 10,
+
+    # orders the response items by highest price
+    order_by: { price: desc },
+
+    # no duplicate prices returned
+    distinct: [ price ]
+    
+    # only items with an id >= 30 and < 30 are returned
+    where: { id: { and: { greater_or_equals: 20, lt: 28 } } }) {
+    id
+    name
+    price
+  }
+}