Some AWS service integration are not supported by the sdk, for instance ECS/Fargate with callback pattern :https://docs.aws.amazon.com/step-functions/latest/dg/connect-supported-services.html.

This PR improve service integration and support callback pattern for ECS/Fargate.

2 options has been removed : 'wait_for_callback' and 'wait_for_completion' and a new one has been added : 'integration_pattern'.
As we have 3 choices Request, Sync and Callback boolean option does not suit well this is why this PR adds an enum to manage the service integration pattern. So we now need to pass the wanted pattern as :

step = BatchSubmitJobStep('Batch Job', integration_pattern=IntegrationPattern.RequestResponse)
where integration_pattern can take following values :

• IntegrationPattern.RequestResponse
• IntegrationPattern.RunAJob
• IntegrationPattern.WaitForCallback

I have used documentation terminology. It is a breaking change but IMHO, the 2 options wait_for_* should not be kept.

I also refactored a bit Task class to check if pattern if supported by a given service, and to automatizeField.Resource.value generation.

All unit tests are OK, I am not able to perform integ test right now but it should have no impact.
I am not sure how to test the documentation generation, what should I do to check that documentation is OK ?

Let me know if some part are not clear or if we could do better, I am not sure about the "name" and "action" Task class attribute but it helps simplifyingField.Resource.value value generation and error management, what do you think ?

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