WAIT task should have a timeout feature

[AntonYudin]

The WAIT task that is waiting for a signal from an external system should support a timeout - this would allow designing a flow that can work in a situation where the external system fails to send a signal.
If the Conductor's main function is to orchestrate other systems through HTTP calls and signals, a timeout in this situation is a must.

In my specific example, I have an ETL process (Apache NIFI) that waits for files to be uploaded by a third party. This process prepares a payload and sends a signal to the conductor notifying it that this step of the flow is complete and the Conductor can call web services that will work with the data.

The conductor flow is scheduled and that allows a visual representation of which step is complete and which has failed.
If the conductor supported the timeout for the WAIT task, looking at the timeline of the flow would make it obvious that this step failed and, which is even more important, would allow sending a notification about the failed step.

Right now the flow will not timeout or fail.

A workaround would be an external process that examines the flows periodically using the Conductors REST api and finds all WAIT tasks that have been waiting for too long and send notifications. This is a very hacky solution.

Here is the link to the original ticket:
#1146

Thanks.