Create pydantic model for pipeline config files

We need to research feasibility of validating config files using pydantic, especially when @JenySadadia will complete migration to v2.

Start by reviewing the pipeline configuration file handling and the planned migration to Pydantic v2. Assess whether the current configuration structure can be represented and validated with Pydantic, and document the feasibility and resulting scope; the issue names no files or tests to run.

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