PartnerAppAuthProvider class support missing in 3.x (similar to 2.x)

**Describe the feature you'd like**
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PartnerAppAuthProvider is the entity used by Sagemaker Partner AI Apps to use for their apps functionality using sagemaker python sdk.

**How would this feature be used? Please describe.**
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Please see https://github.com/aws/sagemaker-python-sdk/blob/master-v2/src/sagemaker/partner_app/auth_provider.py

**Describe alternatives you've considered**
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**Additional context**
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Empieza leyendo la implementación referenciada en master-v2/src/sagemaker/partner_app/auth_provider.py y compárala con la estructura del paquete 3.x. Identifica la ubicación correspondiente y las pruebas para la autenticación de aplicaciones asociadas en 3.x y, a continuación, verifica que PartnerAppAuthProvider esté expuesto y admita el caso de uso documentado de SageMaker Partner AI Apps.

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