Migrate hellaswag benchmark to Inspect Evals

[jjallaire-aisi]

Reminder to pickup moved evals in examples.yaml as well

[MSchmatzAISI]

Quick question - why are these being moved into src/inspect_evals? Is the plan to move every eval there after some quality checks?

[jjallaire-aisi]

inspect_evals is a proper Python module (so easier to have dependencies for than standalone source files). Further, the evals can now be run by just referencing their name rather than their filesystem path:

inspect eval inspect_evals/drop 

It's also easier for other Python code to import and use the tasks when they are in a proper module.

The plan is that everything goes into inspect_evals (there will be no more evals)