Draft: Emit some issue events to AutoFlow

What does this MR do and why?

This change set introduces some new events for issues:

• created
• updated
• closed
• reopened

They are based on the EventStore.

The events come with associated workers to forward those events to AutoFlow as part of AutoFlow PoC: configurable automation for issue... (&12571).

We will most definitely have to adjust the worker configurations to meet AutoFlows requirements - once properly specified.

Refs Add more triggers for autoflow (#443486)

Testing

• You may setup AutoFlow in GDK as described in https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/autoflow.md
• Enable feature flags (autoflow_enabled and autoflow_issue_events_enabled)
• Implement basic Flow script in some project in .gitlab/autoflow/main.star:

def output_event_data(w, ev):
    print("Handling test event: " + ev["type"] + " with data: " + str(ev["data"]))

on_event(
    type="com.gitlab.events.issue_created",
    handler=output_event_data,
)

on_event(
    type="com.gitlab.events.issue_updated",
    handler=output_event_data,
)

on_event(
    type="com.gitlab.events.issue_closed",
    handler=output_event_data,
)

on_event(
    type="com.gitlab.events.issue_reopened",
    handler=output_event_data,
)

• Create, Update, Close and Reopen an issue in that project
• Verify KAS output that you see the prints from the output_event_data handler of the Flow script.