ENH: persisting tasks on a per-run basis

Start with the making tasks persist tutorial and the existing @pytask.mark.persist behavior. Trace how task freshness and database updates are determined, then define the per-run override options and their effects on later executions. Done means the runtime API is documented, preserves existing defaults, and has tests for rerunning, marking updated, and leaving a task stale.

Is your feature request related to a problem?

I'm taking about https://pytask-dev.readthedocs.io/en/stable/tutorials/making_tasks_persist.html

If I format my tasks.py file or update an unrelated task in there, then pytask will re-run the tasks. But I don't want this. I also don't want this to be a permanent feature of the task, as marked with a decorator.

Describe the solution you'd like

I want to be able to specify on a per-run basis whether or not to re-run a task if the source file changed. Ideally it should be something like

• Keep the @pytask.mark.persist as marking default behavior: If its not present, the default is to re-run on src changes. If it is present, then the default is to NOT re-run on source changes. Therefore, we don't break the old API.
• But, add a flag/API at runtime to override this default: On a per-task level be able to change the behavior. I the options should be "rerun", "don't rerun, and mark as updated", and "don't rerun, but don't mark as updated, so next time you run then the task will still appear stale". Maybe I'm not breaking down these options along the right axes, it could use more work.

API breaking implications

Per above, it shouldn't be breaking

Describe alternatives you've considered

Perhaps this warrants re-thinking the API for determining what is "up to date". Per those docs above:

Internally, the state of the dependencies, the source file, and the products are updated in the database such that the subsequent execution will skip the task successfully.

If we accumulate many more edge cases for when a task is up to date, things are going to get complicated. If there was a more official API when you define a task, eg @pytask.Task(func, ins, outs, *, should_run = None) and you could pass in (really brainstorming here)

• None (keep default behavior)
• True (rerun every time)
• A Callable[[Not sure what the args should be], bool]
• "on_dependency_change"
• "on_source_change"
• An Iterable of any of the above. If any are true, then rerun.