Add name to accelerator interface

[justusschock]

What does this PR do?

Adds a name function to Accelerator interface.

Allows accelerator type checks that are agnostic to the package.

E.g. isinstance(accelerator, lightning.fabric.CUDAAccelerator) doesn't work for lightning_fabric.CUDAAccelerator.
And in the future we can check for accelerator.name() == "cuda".

All of those checks we have inside the package are converted properly, but external code cannot properly rely on package-agnostic type-checks.

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• Did you list all the breaking changes introduced by this pull request?
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[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu-guardian	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py.

🟢 pytorch_lightning: lit GPU

Check ID	Status
pytorch.yml / Lit Job (nvidia/cuda:12.1.1-devel-ubuntu22.04, pytorch, 3.10)	success	✅
pytorch.yml / Lit Job (lightning, 3.12)	success	✅
pytorch.yml / Lit Job (pytorch, 3.12)	success	✅

These checks are required after the changes to src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py, src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py.

🟢 Benchmarks

Check ID	Status
benchmark.yml / Lit Job (fabric)	success	✅
benchmark.yml / Lit Job (pytorch)	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py.

🟢 fabric: Docs

Check ID	Status
docs-make (fabric, doctest)	success	✅
docs-make (fabric, html)	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py.

🟢 lightning_fabric: CPU workflow

Check ID	Status
fabric-cpu-guardian	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, tests/tests_fabric/accelerators/test_registry.py.

🟢 lightning_fabric: lit GPU

Check ID	Status
fabric.yml / Lit Job (nvidia/cuda:12.1.1-devel-ubuntu22.04, fabric, 3.10)	success	✅
fabric.yml / Lit Job (fabric, 3.12)	success	✅
fabric.yml / Lit Job (lightning, 3.12)	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, tests/tests_fabric/accelerators/test_registry.py.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py.

🟢 install

Check ID	Status
install-pkg-guardian	success	✅

These checks are required after the changes to src/lightning/fabric/accelerators/accelerator.py, src/lightning/fabric/accelerators/cpu.py, src/lightning/fabric/accelerators/cuda.py, src/lightning/fabric/accelerators/mps.py, src/lightning/fabric/accelerators/xla.py, src/lightning/pytorch/accelerators/cpu.py, src/lightning/pytorch/accelerators/cuda.py, src/lightning/pytorch/accelerators/mps.py, src/lightning/pytorch/accelerators/xla.py.

---

Thank you for your contribution! 💜

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87%. Comparing base (739cf13) to head (fa06094).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #21325     +/-   ##
=========================================
+ Coverage      80%      87%     +7%     
=========================================
  Files         270      270             
  Lines       23764    23799     +35     
=========================================
+ Hits        19040    20629   +1589     
+ Misses       4724     3170   -1554