add script to upgrade to SageMaker Python SDK v2

[ajaykarpur]

Issue #, if available:
aws/sagemaker-python-sdk#1459

Description of changes:
This script upgrades the SageMaker Python SDK to v2 in all Python 3 environments.

Testing Done

• Notebook Instance created successfully with the Lifecycle Configuration
• Notebook Instance stopped and started successfully
• Documentation in the script around any network access requirements
• Documentation in the script around any IAM permission requirements
• CLI commands used to validate functionality on the instance
• New script link and description added to README.md

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[ajaykarpur]

@jaipreet-s great suggestion-- I've added logging and tested end-to-end.