Notifications-lib package for DTOs + commands

[techsmyth]

Description

As a developer I want to have a maintainable way of managing the interactions between the microservices in usage in the platform

Acceptance criteria

• [ ] Make notifications repo to have two packages: notifications-lib, notifications-service (monorepo)
• [ ] notifications-lib: has DTO definitions for all the incoming and outgoing payloads, as well as enum for message types supported. This package to be published as "@alkemio/notifications-lib" in NPM.
• [ ] notifications-service: has what is the actual service (builds to a docker image), and then uses the notifications-libpackage
• [ ] server: updated to alkemio/notifications-lib package, replacing the current notificationes.event.type enum and notifications service payload definitions.
• [ ] Update the build pipelines to reflect the new code structure

Additional Context

[hero101]

• The suggested 'client' is not a client at all IMO - it's a library of types that have to be used for input/output operations.