SLSCMN-8 email service

[mwarman]

📢 Instructions

• Begin with a DRAFT pull request.
• Follow italicized instructions to add detail to assist the reviewers.
• After completing all checklist items, change the pull request to READY.

---

🔧 Change Summary

List the changes included in this pull request.

• Issue: SLSCMN-8
• Create an email service and types to encapsulate the functionality to send emails to the LeanStacks email microservice

📝 Checklist

Pull request authors must complete the following tasks before marking the PR as ready to review.

• Complete a self-review of changes
• Unit tests have been created or updated
• The code is free of [new] lint errors and warnings

🧪 Steps to Test

Describe the process to test the changes in this pull request.

1. Unit tests pass
2. No lint messages

🔗 Additional Information

Optionally, provide additional details, screenshots, or URLs that may assist the reviewer.

• The LeanStacks email microservice receives requests to send transactional email from a SQS queue. Therefore, this Email service serves as a client, placing a standardized message payload into a SQS Queue.