feature: Add Send Notification Email Endpoint

[itsmostafa]

Add send notification email endpoint

🗣 Description

Updated all endpoints with url prefix tasks/ to avoid conflict with con-pca-api endpoints and the frontend
Added NewSESEmail so that it can be initialized once for performance benefits

💭 Motivation and context

Create an endpoint that will eventually be consumed by con-pca-api for manually sending notification emails

🧪 Testing

tested locally

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All relevant repo and/or project documentation has been updated
  to reflect the changes in this PR.
• Tests have been added and/or modified to cover the changes in this PR.
• All new and existing tests pass.

[izzy64]

LGTM