feat: Add user's email to JSON response of egress request

[nguyen102]

Issue #, if available:

Description of changes:
Per new customer requirements I've added two new fields to the response of an Egress Data request. The new fields are updated_by_email and created_by_email.

Testing
I deployed the new code, submitted an egress request, and checked that the response has the newly added fields.

{
    "egress_store_object_list_location": "<REDACTED>/sagemaker-11-egress-store-ver1.json",
    "id": "<REDACTED>",
    "egress_store_id": "<REDACTED>",
    "egress_store_name": "sagemaker-11-egress-store",
    "created_at": "2021-10-15T19:03:09.367Z",
    "created_by": "<REDACTED>",
    "created_by_email": "<REDACTED>@amazon.com",
    "workspace_id": "<REDACTED>",
    "project_id": "proj-new-account-1",
    "s3_bucketname": "<REDACTED>",
    "s3_bucketpath": "<REDACTED>/",
    "status": "PENDING",
    "updated_by": "<REDACTED>",
    "updated_by_email": "<REDACTED>@amazon.com",
    "updated_at": "2021-10-25T18:45:02.883Z",
    "ver": 1
}

Checklist:

• Have you successfully deployed to an AWS account with your changes?
• Have you written new tests for your core changes, as applicable?
• Have you successfully tested with your changes locally?

AS review ticket id:

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

[codecov]

Codecov Report

Merging #771 (0fa76cf) into develop (b10f4b0) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #771   +/-   ##
========================================
  Coverage    52.09%   52.10%           
========================================
  Files          272      272           
  Lines        14519    14522    +3     
  Branches      2285     2285           
========================================
+ Hits          7563     7566    +3     
  Misses        6106     6106           
  Partials       850      850           

Impacted Files	Coverage Δ
lib/data-egress/data-egress-service.js	95.41% <0.00%> (+0.05%)	⬆️

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[SanketD92]

LGTM