Add ngen.config_gen subpackage and MVP for generating init config files

[aaraney]

Add ngen.config_gen subpackage and MVP for generating init config files

ngen.config_gen - 0.0.1

Additions

• ngen.config_gen subpackage
• Configuration generation implementation for CFE, PET, and NoahOWP modules (more coming soon).
• Examples for generating init config files.

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️