Implement extension: service_email_dispatcher

[RHDZMOTA]

The idea of this extension is simple:

• Interact via REST API
• Dispatch single or batch emails

How to authenticate? The idea of this service is to be available in a private network and use simple authentication via a combination of a passkey and json web tokens.

The extension will have 2 different modules:

• The client module
• The service module

The service module will have the following components:

• A REST API Gateway implemented with Fask to receive authentication and email dispatch requests.
• Internal queues: one redis queue per "email server"
• N-workers per queue

Considerations: the service should be able to be used as a CLI and REST API.