Add device property to lazy load functionality

[t-vi]

This adds the .device property and the method .to to NotYetLoaded tensors produced by lazy loading.

The two would be convenient to have for Thunder.

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📚 Documentation preview 📚: https://pytorch-lightning--20183.org.readthedocs.build/en/20183/

cc @Borda @carmocca @justusschock @awaelchli

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-13, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (macOS-14, lightning, 3.10, 2.1)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.2)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.3)	success	✅
pl-cpu (macOS-14, lightning, 3.12, 2.4)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.2)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.3)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.12, 2.4)	success	✅
pl-cpu (windows-2022, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.2)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.3)	success	✅
pl-cpu (windows-2022, lightning, 3.12, 2.4)	success	✅
pl-cpu (macOS-14, pytorch, 3.9, 2.1)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.9, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.9, 2.1)	success	✅
pl-cpu (macOS-12, pytorch, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.10, 2.1)	success	✅

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🟢 pytorch_lightning: Azure GPU

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pytorch-lightning (GPUs) (testing Lightning | latest)	success	✅
pytorch-lightning (GPUs) (testing PyTorch | latest)	success	✅

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🟢 pytorch_lightning: Benchmarks

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lightning.Benchmarks	success	✅

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🟢 fabric: Docs

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docs-make (fabric, html)	success	✅

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🟢 lightning_fabric: CPU workflow

Check ID	Status
fabric-cpu (macOS-13, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (macOS-14, lightning, 3.10, 2.1)	success	✅
fabric-cpu (macOS-14, lightning, 3.11, 2.2)	success	✅
fabric-cpu (macOS-14, lightning, 3.11, 2.3)	success	✅
fabric-cpu (macOS-14, lightning, 3.12, 2.4)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.11, 2.2)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.11, 2.3)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.12, 2.4)	success	✅
fabric-cpu (windows-2022, lightning, 3.9, 2.1, oldest)	success	✅
fabric-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
fabric-cpu (windows-2022, lightning, 3.11, 2.2)	success	✅
fabric-cpu (windows-2022, lightning, 3.11, 2.3)	success	✅
fabric-cpu (windows-2022, lightning, 3.12, 2.4)	success	✅
fabric-cpu (macOS-14, fabric, 3.9, 2.1)	success	✅
fabric-cpu (ubuntu-20.04, fabric, 3.9, 2.1)	success	✅
fabric-cpu (windows-2022, fabric, 3.9, 2.1)	success	✅
fabric-cpu (macOS-12, fabric, 3.10, 2.1)	success	✅
fabric-cpu (ubuntu-22.04, fabric, 3.10, 2.1)	success	✅
fabric-cpu (windows-2022, fabric, 3.10, 2.1)	success	✅

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lightning-fabric (GPUs) (testing Fabric | latest)	success	✅
lightning-fabric (GPUs) (testing Lightning | latest)	success	✅

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🟢 mypy

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🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, fabric, 3.9)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.9)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.9)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.9)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-12, fabric, 3.9)	success	✅
install-pkg (macOS-12, fabric, 3.11)	success	✅
install-pkg (macOS-12, pytorch, 3.9)	success	✅
install-pkg (macOS-12, pytorch, 3.11)	success	✅
install-pkg (macOS-12, lightning, 3.9)	success	✅
install-pkg (macOS-12, lightning, 3.11)	success	✅
install-pkg (macOS-12, notset, 3.9)	success	✅
install-pkg (macOS-12, notset, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.9)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.9)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.9)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.9)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

These checks are required after the changes to src/lightning/fabric/utilities/load.py.

---

Thank you for your contribution! 💜

Note
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89%. Comparing base (828fd99) to head (6ff534e).
Report is 26 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #20183   +/-   ##
=======================================
  Coverage      89%      89%           
=======================================
  Files         267      267           
  Lines       23079    23082    +3     
=======================================
+ Hits        20580    20583    +3     
  Misses       2499     2499           

[awaelchli]

Thanks Tom 🎉