fix: add multi-user-project byod scenario and updated ReadMe for potential errors + workarounds

[svia3]

…ntial errors + workarounds

Issue #, if available:

• Address the scenario where user whats to in addition to flow A - link project B, created environment B, subset of usersB to create a punch out link for flow B.
• update README to add some helpful common errors and workarounds

Description of changes:

• loop on critical linking functionality
• remove fed role as arg param in exchange for input during script execution as to enable FedRoleA to be used on first pass, and FedRoleB to be used on second.

Testing done:

• manual using two different roles in HULK testing account
• Project A, Environment A, UserA that has ExecutionRole A and FederationRole A -> generate punch out link and verify assets appear in studio UI. Same for flow B.

Merge Checklist

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• I have verified that my PR does not contain any new notebook/s which demonstrate a SageMaker functionality already showcased by another existing notebook in the repository
• I have read the CONTRIBUTING doc and adhered to the guidelines regarding folder placement, notebook naming convention and example notebook best practices
• I have updated the necessary documentation, including the README of the appropriate folder as well as the index.rst file
• I have tested my notebook(s) and ensured it runs end-to-end
• I have linted my notebook(s) and code using python3 -m black -l 100 {path}/{notebook-name}.ipynb

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