Encryption

[chaithanya77]

Issue #, if available:
Description of changes:

Enabling default encryption on SNS, SQS and S3. Using AWS managed SSE, so no additional IAM changes needed. Tested the changes with a new product.

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[linhlam-mp]

Hi, Can you help to share more information of end to end testing with these changes following the form below?

**End-to-end ("e2e")**: These are broad tests of overall system behavior and coherence. Please test and confirms these itemsL
    1. Verify the stack is deployed successfully.
    2. Verify URL endpoint is up and running with no error.
    3. Subscribe to the product successfully and can visit landing page with no error.
    4. Create an account using landing page.
    5. Receive notification as a Seller.
    6. Receive notification as a Buyer.
    7. Verify new user record is created in Amazon DynamoDB.

In addition, can you add more comment around why the changes are needed and if there are any trade-offs (e.g: SQS queue could not invoke lambda function from different AWS account if it is encrypted)