fix(datastore): List errors that are returned from AppSync

[mattcreaser]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:
Improve logging of errors returned from AppSync. We previously erroneously reported a response with errors as an "empty response" which limits ability to diagnose the error. We will now include the actual error in the log message.

Before:

IrRecoverableException{message=Empty response from AppSync., cause=null, recoverySuggestion=Report to AWS team.}

After:

IrRecoverableException{message=Received errors from AppSync: GraphQLResponse.Error{message='Not Authorized to access syncGuests on type Query', locations='[GraphQLLocation{line='2', column='3'}]', path='[GraphQLPathSegment{value='syncGuests'}]', extensions='{errorInfo=null, data=null, errorType=Unauthorized}'}, cause=null, recoverySuggestion=Report to AWS team.}

How did you test these changes?
(Please add a line here how the changes were tested)

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

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