[Ingest Manager] Send status to fleet during checkin

[michalpristas]

As for this PR elastic/kibana#71009 fleet enables us to specify online, error or degraded state.

We need to send it to fleet based on healthchecks we run and make sure we reset it to ok when issue is transient.

cc @ph @blakerouse

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[ph]

I think we should consider this a bug.
@blakerouse does this require a lot of change on our side?

[blakerouse]

It's like a 1 line change. I would consider it a bug as well.

[ph]

@blakerouse I think that was fixed in #19857 ?

[blakerouse]

No this is different. A new top level field of status was added to checkin, which we need to instrument a way to calculate that status. At the moment Agent doesn't compute an overall status for the Agent to send to Fleet.

[blakerouse]

This was done a while ago, just forgot to close.