gh-152297: Reify dotted lazy imports with the full dotted name

[Kuhai9801]

Fix lazy reification for dotted imports so lazy import pkg.sub calls __import__ with the full dotted name, matching eager import behavior.

The regression tests cover custom __import__ hooks and first-use loading of the dotted target.

Tests:

• git diff --check
• GitHub Actions required checks after squash

• Issue: Dotted lazy import reification bypasses full-name __import__ hook #152297

[python-cla-bot]

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[Kuhai9801]

The remaining Emscripten failure appears unrelated to this PR; it fails in test_profiling thread startup, outside the lazy-import changes.

[pablogsal]

Thanks for the PR! I think this still misses one dotted import case.

[pablogsal]

Unless I am missing something, lazy import pkg.sub as alias still misses this. That path goes through _PyEval_LazyImportFrom() and reifies as __import__("pkg", fromlist=("sub",)), while eager import pkg.sub as alias calls __import__("pkg.sub", fromlist=()). We should fix/test that case as well.

[pablogsal]

Sorry I am going to also close this PR. You keep using AI without reviewing the code is producing and this is making review harder. You also keep adding api functions to everywhere which I don't understand why is needed. You are not weighting on the changes you produce

Please stop this behavior or we will need to escalate