Formulation configuration refactoring

[hellkite500]

Builds on #743. This will nearly decouple Formulation_Manager from boost ptrees. There are still a couple places which are dependent on the ptree, but it is now only the highest level of extracting the main components and building configuration strcutures which are used throughout the rest of the formulation manager code.

Additions

• Forcing configuration structure
• Formulation configuration structure
• Config structure which pairs Formulations with potential Forcing

Removals

Changes

• Most configuration parsing logic, such as linking external parameters, is now isolated and managed in the config structures and methods.
• construct_formulation_from_tree renamed to construct_formulation_from_config and no longer requires any ptree inputs, but instead uses the constructed configuration objects.

Testing

1. All existing tests pass with the refactored code
2. Fixed one test realization to include a required key that was previously missing

Todos

• A subsequent PR will address Layer configuration and mechanics

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 ➡️

Target Environment support

• Linux
• MacOS