Create Azure function project for events

[EliuX]

We need to handle all actions that occur in the API. For that purpose, we have designed a model for events, which are going to be handled by a new Azure Function app, e.g. events-functions. The serverless app and the API one will be connected thanks to Change Feed.

TODO:

• Firstly, we need to create this new Azure Function App in order to handle all actions over events.
• We need to design a model for Cosmos DB and create the corresponding migration so we are ready to generate events.
• Create the functions for handling the events. They should be ready to be tested from the Azure function UI.