List of high level APIs for the MVP

[spannercode]

This is a placeholder ticket for listing all high level APIs for the mail service. This should include the following:

1. API to send email (refer sendgrid API)
2. Templates API
3. Contacts API (subscribe/unsubscribe)
4. APIs for the Dashboard (overview/stats)

[Kanak1125]

1. API to send email (refer sendgrid API)
   GET /api/emails/:emailId - Get the email from id (used for the draft)
   POST /api/emails/send - Send an email
   PATCH /api/emails/:emailId- Update the drafted email before sending it.
   DELETE /api/emails/:emailId - Delete the draft for the email.

2. Templates APIs
   GET /api/templates - Get templates
   POST /api/templates - Create a new template
   PATCH /api/templates/:templateId - Update a template
   DELETE /api/templates/:templateId - delete a template

3. Contacts API (subscribe/unsubscribe)
   GET /api/contacts/:listId - Get all the contacts associated with the contact list of specific id
   POST /api/contacts/:listId - Create a new contact
   PATCH /api/contacts/:contactId - Update the contact's status (subscribe / unsubscribe )
   DELETE /api/contacts/:contactId - Delete a contact
   GET /api/contacts - Get all the contacts regardless of the contact lists.

4. APIs for the Dashboard (overview/stats)
   GET /api/dashboard/stats - Get the stats data