[AIRFLOW-6882] Implement SageMakerHook list_training_jobs method + convenience method for iterating list_* requests

[BasPH]

The SageMakerHook currently does not support any list_* operations (there are a few... https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sagemaker.html). This PR adds a generic method for iterating over list_* operation results and one implementation for list_training_jobs.

By default, boto3 caps the number of results to 10. This is configurable up to 100. I've implemented _list_request as a convenience function for making multiple requests to AWS in case more results are available. SageMakerHook.list_training_jobs() makes use of this convenience function.

Not sure if tests should be added because all existing SageMakerHook tests simply test the number of calls to the underlying client's methods, which doesn't really validate correct behaviour IMO?

Example usage:

from airflow.providers.amazon.aws.hooks.sagemaker import SageMakerHook

hook = SageMakerHook()
hook.list_training_jobs(max_results=150)

Say there are 2000 training jobs, then _list_request() will select 150 training jobs in 2 batches (first 100, next 50).

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Issue link: AIRFLOW-6882

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[BasPH]

Closing in favour of #7598