[USER MODERATION] - 2nd deliverable - user after actions

[alejandromumo]

When a user is moderated (e.g. blocked), some actions might need to be triggered. E.g:

• User is blocked
• User records and communities must be deleted

In this issue we should come up with a mechanism to register these "after actions" and execute them.

There are some concerns to be taken into consideration:

• Actions can take some time to execute (e.g. deleting hundreds or thousands of records)
• We must be aware of consistency. E.g. if the user status is "blocked" then we expect that everything was deleted. Intermediary states are not expected (e.g. user is blocked but records still exist in the system).