Group modeling and other assorted updates

[bradmiller]

This PR includes the following changes:

• Support for "modeling groups" to improve coverage over subsets of the data
• Improved model convergence logic to reduce scoring instability
• Increasing the required confidence for CRHing notes based on confidence intervals
• Support for running a subset of scoring logic for development purposes
• Support for computing separate training and validation loss during development
• Turndown of the coverage model which trialed an expansion of CRH notes through modified regularization

[CLAassistant]

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[Sulxl]

review