Add checkpointing tests

[ankitgola005]

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• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

Fixes # (issue).

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[ankitgola005]

Manual testing results.
Note: To be rebased over #251.

Category	pytorch-lightning | pypi		pytorch-lightning | source		lightning | pypi		lightning | source
	G1	G2	G1	G2	G1	G2	G1	G2
HPU General tests	P	P	P	P	P	P	P	P
HPU torch compile tests	P	P	P	P	P	P	P	P
HPU FSDP tests	P	P	P	P	P	P	P	P
HPU Deepspeed tests	P	P	P	P	P	P	P	P
HPU precision test	P	P	P	P	P	P	P	P
Standalone-only single card tests	P	P	P	P	P	P	P	P
Multi card(2) HPU test	P	P	P	P	P	P	P	P
FSDP PT Multi card(2) HPU test	P	P	P	P	P	P	P	P
FSDP Fabric Multi card(2) HPU test	P	P	P	P	P	P	P	P
Testing HPU examples	P	P	P	P	P	P	P	P