feat: add validate directive and transformer package

[bobbyu99]

Description of changes

This PR added a new @validate directive and a graphql-validate-transformer package.

Detail of changes:

• set up a new graphql-validate-transformer package with some package configurations
  • added ValidateTransformer class that does nothing for now
  • added 1 skeleton test file
• updated a bunch of package.json with the new graphql-validate-transformer package
• updated snapshot test and transformer test to acknowledge the new transformer
• added ValidateTransformer to transformer chain
• added @validate directive definitions (API approved)

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• E2E test run linked
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• Any CDK or CloudFormation parameter changes are called out explicitly

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

[bobbyu99]

Pending API review for:

directive @validate(
  type: ValidationType!,
  value: String!,
  errorMessage: String
) on FIELD_DEFINITION

enum ValidationType {
  gt
  lt
  gte
  lte
  minLength
  maxLength
  startsWith
  endsWith
  matches
}

Update:
API approved.