More friendly app name definition

[benclifford]

Is your feature request related to a problem? Please describe.

Traditional original-generation Parsl takes the app name for a task from user-decorated app function. This works when a user is using the traditional "define a workflow using Parsl syntax".

Parsl increasingly has users doing more interesting programming-language stuff where the directly decorated function often doesn't have a name that reflects what the user might perceive as their real task name.

As an example, the bps workflow system uses Parsl as an underlying workflow system. There is a bps-level notion of a task name and it makes sense for that task name to be the parsl app name in logs and monitoring, rather than a generic job_run_command wrapper. bps + gen3_workflow works around this by defining a new wrapper every time, with no new code but the __name__ attribute populated from the bps level task - this is awkward trickery.

https://github.com/LSSTDESC/gen3_workflow/blob/dfb717bc665985018ad4b3135272abd60023c362/python/desc/gen3_workflow/parsl_service.py#L179

Describe the solution you'd like
Treatment of app name definition in ways other than directly extracting a name from the wrapped function.

I don't have any particular preferences on how this is done: it could be documentation, it could be a value in parsl_resource_spec, it could be a new decorator parameter...

Additional context
Lots of users mention this without anyone really bringing it up as a super-high priority must-have feature request.