[DRAFT]: Add checkpointing for FSDP2
<!-- pylint-output-strict-mode-false -->

beep boop 🤖: 🙏 The following files have warnings. In case you are familiar with these, please try helping us to improve the code base.

---

Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module hf
examples/llm/peft/hf.py:60:0: C0301: Line too long (184/119) (line-too-long)
examples/llm/peft/hf.py:56:0: C0116: Missing function or method docstring (missing-function-docstring)
examples/llm/peft/hf.py:95:0: C0116: Missing function or method docstring (missing-function-docstring)
examples/llm/sft/hf.py:71:0: C0301: Line too long (184/119) (line-too-long)
examples/llm/sft/hf.py:137:0: C0301: Line too long (162/119) (line-too-long)
examples/llm/sft/hf.py:67:0: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.63/10
```

---

Mitigation guide:

* Add sensible and useful docstrings to functions and methods
* For trivial methods like getter/setters, consider adding `# pylint: disable=C0116` inside the function itself
* To disable multiple functions/methods at once, put a `# pylint: disable=C0116` before the first and a `# pylint: enable=C0116` after the last.

By applying these rules, we reduce the occurance of this message in future.

Thank you for improving NeMo's documentation! <!-- pylint-output-strict-mode-true -->

beep boop 🤖: 🚨 The following files must be fixed before merge!

---

Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.lightning.pytorch.strategies.fsdp2_strategy
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:98:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:104:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:129:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:159:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:168:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:178:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:186:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:194:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/strategies/fsdp2_strategy.py:215:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.33/10
```

---

Mitigation guide:

* Add sensible and useful docstrings to functions and methods
* For trivial methods like getter/setters, consider adding `# pylint: disable=C0116` inside the function itself
* To disable multiple functions/methods at once, put a `# pylint: disable=C0116` before the first and a `# pylint: enable=C0116` after the last.

By applying these rules, we reduce the occurance of this message in future.

Thank you for improving NeMo's documentation!
# What does this PR do ?

Add a one line overview of what this PR aims to accomplish.

**Collection**: [Note which collection this PR will affect]

# Changelog 
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# Usage
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```python
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