Implement PEP 798

[adqm]

Proposal:

This is a tracking issue for implementing PEP 798 (Unpacking in Comprehensions).

Links to previous discussion of this feature:

• https://discuss.python.org/t/pre-pep-unpacking-in-comprehensions/96362
• https://discuss.python.org/t/pep-798-unpacking-in-comprehensions/99435

Linked PRs

• gh-143055: Implementation of PEP 798 #143056