EmailConnector: Send Erasure Email /Test Email

[pattisdr]

Is your feature request related to a specific problem?

Send an email to a third party source at the configured email address to instruct them to mask/erase data. Also allow the EmailConnector to be tested, so a Fidesops user can send an email to themselves to preview what we're sending through the EmailConnector.

Describe the solution you'd like

• Update the EmailConnector.test_connection method to generate a fake email to send to the user at ConnectionConfig.secrets.test_email if configured.
• Update the EmailConnector.mask_data method to send an email to the user instructing them how to mask data for the given collection.
  • Design question: Should we send one email per collection (happens as part of the traversal), or one email per privacy request? It's also been brought up that we may need to batch these emails in the future too. ANSWER: For now, we are sending one email per privacy request, but batching has been postponed.

Describe alternatives you've considered, if any

A description of any alternative solutions or features you've considered.

Additional context

• We'll also need some basic copy for this email to generate a starter email template.

Blocked by: #1135