SWA Granite HF registration

[yannicks1]

Description

Drops the dependency on the granite-swa-model transformers fork. Routes granite_swa through the generic FMS hf_pretrained/hf_configured path. Pairs with this FMS registration PR.

Related Issues

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Test Plan

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Checklist

• I have read the contributing guidelines
• My code follows the project's code style (run bash format.sh)
• I have added tests for my changes (if applicable)
• I have updated the documentation (if applicable)
• My commits include a Signed-off-by: line (DCO compliance)

[github-actions]

👋 Hi! Thank you for contributing.
Just a reminder: Make sure that your code passes all the linting checks, otherwise your PR won't be able to be merged. To do so, run ./format.sh.
Now you are good to go 🚀.

We also recommend installing prek and configuring it to check your code before every local commit.

[joerunde]

We could consider adding a test here that loads a model config with granite_swa model_type to flex these code paths. (That might require whipping up a super tiny dummy model, which our good friend claude is also pretty good at.)

Not totally required for the initial merge here, but I would lean towards including because we've shipped a lot of regressions in the past for models like mistral that we didn't have load-path test cases for in the github CI

[yannicks1]

Thanks for reviewing! Added some tests and hit auto-merge :)