feat(api-graphql): Add affected items in the errors object

[Bhavika-Gianey]

Description of changes

Adding affected items when a relationship is deleted while querying for the data. The code takes the initial query data when non-null entities are encountered, generates a new query where all the entities will be present by returning only the id's from the query, and then compares the new response with the previous response to check for null entities. The respected null entities are then pushed back in the response.items array.

Issue #, if available

aws-amplify/amplify-category-api#3233

Description of how you validated changes

I checked the query with the schema table the customer was facing and other tables where non-nullable error messages could be shown and then compared the queries with and without the null returned attributes.

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.