refactor(GraphQL): Rename objectId to id (#5985)

* refactor(GraphQL): Rename objectId to id

Renames `objectId` to `id` for the GraphQL API. Queries, mutations,
custom and generic types were updated.
Removes `RELATION_INPUT` and `POINTER_INPUT`. Now the user just need
to provide the ID of the object to link.

* fix: Column "id" not found on Postgres

* fix: Avoid deleting Parse class objectId

* fix: Undo objectId removal on mutations

* fix: Handle generic mutation id

src/GraphQL/transformers/query.js

@@ -1,4 +1,5 @@
 const parseMap = {
+  id: 'objectId',
   _or: '$or',
   _and: '$and',
   _nor: '$nor',