Feat: Move notifications from core to modules to facilitate customization

[dlpzx]

Feature or Bugfix

• Refactoring

Detail

As a rule of thumb, we encourage customization of modules while changes in core should be avoided when possible. notifications is a component initially in core which is only used by dataset_sharing. To facilitate customization of the notifications module and also to clearly see its dependencies we have:

• Moved notifications code from core to modules as it is a reusable component that is not needed by any core component.
• Moved dataset_sharing references inside dataset_sharing module and left notifications independent from any other module
• Added depends_on in the dataset_sharing module to load notifications if the data_sharing module is imported.

TODO:

• frontend changes in case notifications are not loaded
• not for this PR, but as a general note, we should clean up deprecated ECS tasks

Relates

• Refactor and migrate notifications from core to modules #785
• Email Notification for Actions on Share Requests #734

Security

Please answer the questions below briefly where applicable, or write N/A. Based on
OWASP 10.

N/A just refactoring

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[dlpzx]

@noah-paige and I discussed internally that this PR is just for reference and will stay in Draft. First the PR for #734 needs to be merged and then we will do the necessary changes which developed in this Draft PR.

[dlpzx]

Closing, it will be merged in #822