Task action: "Suspend after next checkpoint"

[pataquets]

Describe the problem
On client shutdown or task suspend, non-checkpointed work is lost. So far, I've found uncheckpointed work for 1h or even 2h worth, which is quite a waste, if stopped and lost.
When an orderly shutdown is possible (eg. reviewing tasks before shutdown/restart), you can wait tasks to checkpoint before suspending/quitting, but it's tedious and inconvenient.
It can be helpful when shutting down, but also for switching tasks/projects.

Describe the solution you'd like
I would like to have a 'Suspend after next checkpoint' task action. Thus, I could send it to all running tasks to guarantee that no work is lost.

Additional context
Assumptions:

• Tasks notify client on checkpoint, which can react accordingly.
• Some tasks do not checkpoint, which is fine. It's up to you to know it if you intend to do "whatever at checkpoint".

This feature would later enable also a 'checkpointed shutdown' for the whole client. You can manually trigger it as a command when winding down before shutdown, set it as an opt-in behaviour on SIGTERM or do it on another signal. Lots of people might find it helpful to avoid wasted work (time and electricity).