make sure the FSDP plugin args are appropriately cast to bools
Author: winglian
Pull request: yes

# What does this PR do?

-  Properly enable FSDP2.
- `accelerate`s `FullyShardedDataParallelPlugin` expects certain args to be bools otherwise the checks don't parse correctly.
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Fixes # (issue)


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Comments:
we also need to remove the `fsdp_` prefix in the version check since it always gets stripped higher up


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