GraphQL Object constraints (#5715)

* GraphQL Object constraints

Implements the GraphQL Object constraints, which allows us to filter queries results using the `$eq`, `$lt`, `$gt`, `$in`, and other Parse supported constraints.
Example:
```
query objects {
  findMyClass(where: {
    objField: {
      _eq: {
        key: 'foo.bar',
        value: 'hello'
      },
      _gt: {
        key: 'foo.number',
        value: 10
      },
      _lt: {
        key: 'anotherNumber',
        value: 5
      }
    }
  }) {
    results {
      objectId
    }
  }
}
```
In the example above, we have the `findMyClass` query (automatically generated for the `MyClass` class), and a field named `objField` whose type is Object. The object below represents a valid `objField` value and would satisfy all constraints:
```
{
  "foo": {
    "bar": "hello",
    "number": 11
  },
  "anotherNumber": 4
}
```
The Object constraint is applied only when using Parse class object type queries. When using "generic" queries such as `get` and `find`, this type of constraint is not available.

* Objects constraints not working on Postgres

Fixes the $eq, $ne, $gt, and $lt constraints when applied on an Object type field.

* Fix object constraint field name

* Fix Postgres constraints indexes

* fix: Object type composed constraints not working

* fix: Rename key and value fields

* refactor: Object constraints for generic queries

* fix: Object constraints not working on Postgres

spec/schemas.spec.js

@@ -425,8 +425,12 @@ describe('schemas', () => {
           foo4: { type: 'Date', required: true },
           foo5: { type: 'Number', defaultValue: 5 },
           ptr: { type: 'Pointer', targetClass: 'SomeClass', required: false },
-          defaultFalse: { type: 'Boolean', required: true, defaultValue: false },
-          defaultZero: { type: 'Number', defaultValue: 0 }
+          defaultFalse: {
+            type: 'Boolean',
+            required: true,
+            defaultValue: false,
+          },
+          defaultZero: { type: 'Number', defaultValue: 0 },
         },
       },
     }).then(async response => {
@@ -447,8 +451,12 @@ describe('schemas', () => {
           foo4: { type: 'Date', required: true },
           foo5: { type: 'Number', defaultValue: 5 },
           ptr: { type: 'Pointer', targetClass: 'SomeClass', required: false },
-          defaultFalse: { type: 'Boolean', required: true, defaultValue: false },
-          defaultZero: { type: 'Number', defaultValue: 0 }
+          defaultFalse: {
+            type: 'Boolean',
+            required: true,
+            defaultValue: false,
+          },
+          defaultZero: { type: 'Number', defaultValue: 0 },
         },
         classLevelPermissions: defaultClassLevelPermissions,
       });
@@ -468,8 +476,8 @@ describe('schemas', () => {
       expect(obj.get('foo4')).toEqual(date);
       expect(obj.get('foo5')).toEqual(5);
       expect(obj.get('ptr')).toBeUndefined();
-      expect(obj.get('defaultFalse')).toEqual(false)
-      expect(obj.get('defaultZero')).toEqual(0)
+      expect(obj.get('defaultFalse')).toEqual(false);
+      expect(obj.get('defaultZero')).toEqual(0);
       expect(obj.get('ptr')).toBeUndefined();
       done();
     });