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. Unresolved placeholders keep the declarations for their package and namespace, while the shared registry keeps the original declarations and selects the matching builtins hook. This keeps the bookkeeping in the import paths; private hook results retain full-path behavior.

• 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 #34941639 | 📁 Comparing 200bac8 against main (e0861c6)

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5 files changed · ± 5 modified

± Modified

• c-api/unicode.html
• reference/simple_stmts.html
• using/configure.html
• whatsnew/3.16.html
• whatsnew/changelog.html