Add Delegates events on creation/deletion/update

[hectorgomezv]

What is needed?

Delegates (proposers) is used on mobile clients only, and the traffic associated with the delegates endpoint is low. However, after the delegates/proposers list is included in the Web UI, we expect a substantial increase in the traffic related to these endpoints.

The CGW strategy was not to cache the results for the delegates/proposers, but considering the traffic increase, it might make sense to add a caching/invalidation strategy.

Technical details

• Create a new event to signal the delegates/proposers' list has changed for a Safe address.
• Send the event to the general RabbitMQ, which is consumed by the CGW.

[JagoFigueroa]

How are the machines? 😎 tested and verified

Un saludito!