Give names to asyncio tasks in Python 3.8+

[nolar]

What do these changes do?

Expose the name/purpose of the asyncio tasks in tests and at runtime in case of failures. Previously, they were anonymous "Task-25" and alike.

Description

For Python 3.7, keep the tasks unnamed (it does not support named tasks):

• https://docs.python.org/3/library/asyncio-task.html#asyncio.Task.set_name
• https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task

Issues

#338

Checklist

• The code addresses only the mentioned problem, and this problem only
• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt