Implement PEP 810 – Explicit lazy imports

[pablogsal]

Linked PRs

• gh-142349: Implement PEP 810 - Explicit lazy imports #142351
• gh-142349: Fix build errors from PEP 810 #144726
• gh-142349: Fix refcount corruption in lazy import specialization #144733
• gh-142349: Add CODEOWNERS for lazy imports #144840
• gh-142349: Fix ast.unparse for lazy import statements #144893
• gh-142349: Move all lazy-imports-by-hand to use the new lazy keyword #144894

[pablogsal]

The __future__ is now :)

[johnslavik]

CC @ZeroIntensity (mentorship): I'd give this a 3.15 too

[ZeroIntensity]

We usually don't add version labels for features, since they always imply the main branch (see the devguide). It's more controversial for bugs, such as in the case yesterday.

[FFY00]

modulefinder will probably need some updating too, or at least documenting it doesn't support PEP 810.

[DinoV]

modulefinder will probably need some updating too, or at least documenting it doesn't support PEP 810.

I suspect there was a test that already made sure this is working. It looks like this relies upon scanning the byte code, and uses dis._find_imports to do so, and that got fixed here: 0b36549

[FFY00]

Ah, great!