Add IO processor for certainty intrinsic

[frreiss]

This PR adds an IO processor for the Granite certainty intrinsic, AKA the Granite 3.2 8B Instruct Uncertainty LoRA.

In addition to the IO processor, I've also added some support functionality to the library:

• A new base class for IO processors that mutate generation arguments, i.e. for constrained decoding
• An implementation of Add back support for captive vLLM server #41 to support testing the new IO processor with the target LoRA adapter

I also include a notebook and test cases.

[frreiss]

Notebook CI tests failing due to disk space issue. Not sure how to fix that.

[hickeyma]

Notebook CI tests failing due to disk space issue. Not sure how to fix that.

Try adding disk cleanup (https://github.com/ibm-granite/granite-io/blob/main/.github/workflows/test.yml#L59C7-L60C48) before setting up Python (https://github.com/ibm-granite/granite-io/blob/main/.github/workflows/test_examples.yml#L58)

[hickeyma]

Only a shallow review not but noticed vLLM backend and also potential fix for the ci disk issue. Will return later to review further.

[frreiss]

Notebook CI tests failing due to disk space issue. Not sure how to fix that.

Try adding disk cleanup (https://github.com/ibm-granite/granite-io/blob/main/.github/workflows/test.yml#L59C7-L60C48) before setting up Python (https://github.com/ibm-granite/granite-io/blob/main/.github/workflows/test_examples.yml#L58)

Thanks, adding that step to the workflow has cleared up the CI issues.

[markstur]

see questions inline

[hickeyma]

@frreiss Some small things

Martin said on internal slack that this was okay

Looks good to go. Just some small comments. @mark.sturdevant I'll leave it to you to decide

... and I feel like we need to merge it and iterate

[markstur]

Let's merge this and then iterate on things like supportability, usability, docs, test limitations...