* Add checked prediction methods
- Add checked prediction methods to ZeroShotClassificationModel.
These methods return Option and convert any underlying errors into None,
to allow callers to implement appropriate error handling logic.
* Update ZeroShot example to use checked method.
* Add tests for ZeroShot checked methods
* Change checked prediction methods to return Result
* refactor: rename *_checked into try_*
Rename *_checked methods into try_* methods.
This is more idiomatic vis-a-vis the Rust standard library.
* refactor: remove try_ prefix from predict methods
* refactor: change return from Option to Result
Change return type of ZeroShotClassificationModel.prepare_for_model
from option into Result. This simplifies the code, and returns
the error closer to its origin.
This addresses comments from @guillaume-be.
* refactor: address clippy lints in tests
Co-authored-by: guillaume-be <guillaume.becquin@gmail.com>
