feat(gen2-migration): media vault test script

[sanjanaravikumar-az]

This script provides comprehensive frontend-backend testing for the Media Vault app's Amplify Gen1 backend.

What it tests:

• GraphQL queries (listNotes, getNote)
• GraphQL mutations (CRUD operations for Notes)
• Lambda function operations (generateThumbnail, addUserToGroup, removeUserFromGroup)
• S3 Storage operations (file upload with Amplify v6 API)

How it works:

• Authenticates via Cognito user pool
• Runs authenticated queries to verify data retrieval (Notes with owner-based access)
• Performs full CRUD cycle on Notes (create → update → delete)
• Uploads test image to S3 using new Amplify v6 path API
• Tests thumbnail generation Lambda function with uploaded image
• Tests user group management Lambda functions (add/remove user from Admin group)
• Cleans up test data (deletes created notes) and signs out

Users need to:

• Update TEST_USER credentials in the script
• Provide a test image path in TEST_IMAGE_PATH

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