gh-158140: Resolve lazy submodules independently with custom import hooks

[pablogsal]

Resolve ordinary packages from the root down, so accessing one lazy submodule doesn't import its siblings. Keep pending declarations by builtins namespace and use the matching namespace's current __import__ hook, while preserving the existing behavior for hooks that return private objects.

• Issue: Accessing one lazily imported submodule (lazy import pkg.a) also imports a later imported pkg.b #158140

[read-the-docs-community]

Documentation build overview

📚 cpython-previews | 🛠️ Build #34936132 | 📁 Comparing 979f879 against main (e0861c6)

  🔍 Preview build  

3 files changed

± reference/simple_stmts.html
± using/configure.html
± whatsnew/changelog.html