Make "as a download" and "obtaining a file name" more explicit

[xyaoinum]

Followup issue for #4450:

It would be better to turn as a download into a more explicit list of steps (if to be aborted, if the resource was successfully obtained, if need a file name, etc.).

Also it would be better to make "obtaining a file name" a more explicit algorithm on its own. Currently the algorithm simply comes after as a download and doesn't have a explicit name.

[Catalyst497]

I would like to work on this one. Is it open?

[annevk]

Yes, this is still a problem worthy of addressing.

[Catalyst497]

Ok. How do I start? I'm a first-timer

[annevk]

The issue is still open, but if you want to address it you'll have to figure out from the README and other instructions in the repository how go about creating a PR. Unfortunately nobody has the bandwidth to walk someone through this at the moment.