Iron: Example with independently sized mine and iron/steel plant

[jmartin4nrel]

Example with independently sized mine and iron/steel plant

This PR changes the iron example (#21) so that the iron_mine can be realistically large and produce a large iron_ore_out stream that is not entirely consumed by the downstream iron_plant. This allows the iron_ore_price to be calculated separately in its own financial subgroup, then passed to the iron_plant via a feedstock.

Early draft PR, tests and docs needed.

Section 1: Type of Contribution

• Feature Enhancement
  • Framework
  • New Model
  • Updated Model
  • Tools/Utilities
  • Other (please describe):
• Bug Fix
• Documentation Update
• CI Changes
• Other (please describe):

Section 2: Draft PR Checklist

• Open draft PR
• Describe the feature that will be added
• Fill out TODO list steps
• Describe requested feedback from reviewers on draft PR
• Complete Section 7: New Model Checklist (if applicable)

TODO:

• Step 1
• Step 2

Type of Reviewer Feedback Requested (on Draft PR)

Structural feedback:

Implementation feedback:

Other feedback:

Section 3: General PR Checklist

• PR description thoroughly describes the new feature, bug fix, etc.
• Added tests for new functionality or bug fixes
• Tests pass (If not, and this is expected, please elaborate in the Section 6: Test Results)
• Documentation
  • Docstrings are up-to-date
  • Related docs/ files are up-to-date, or added when necessary
  • Documentation has been rebuilt successfully
  • Examples have been updated (if applicable)
• CHANGELOG.md has been updated to describe the changes made in this PR

Section 3: Related Issues

Section 4: Impacted Areas of the Software

Section 4.1: New Files

• path/to/file.extension
  • method1: What and why something was changed in one sentence or less.

Section 4.2: Modified Files

• path/to/file.extension
  • method1: What and why something was changed in one sentence or less.

Section 5: Additional Supporting Information

Section 6: Test Results, if applicable

Section 7 (Optional): New Model Checklist

• Model Structure:
  • Follows established naming conventions outlined in docs/developer_guide/coding_guidelines.md
  • Used attrs class to define the Config to load in attributes for the model
    • If applicable: inherit from BaseConfig or CostModelBaseConfig
  • Added: initialize() method, setup() method, compute() method
    • If applicable: inherit from CostModelBaseClass
• Integration: Model has been properly integrated into H2Integrate
  • Added to supported_models.py
  • If a new commodity_type is added, update create_financial_model in h2integrate_model.py
• Tests: Unit tests have been added for the new model
  • Pytest-style unit tests
  • Unit tests are in a "test" folder within the folder a new model was added to
  • If applicable add integration tests
• Example: If applicable, a working example demonstrating the new model has been created
  • Input file comments
  • Run file comments
  • Example has been tested and runs successfully in test_all_examples.py
• Documentation:
  • Write docstrings using the Google style
  • Model added to the main models list in docs/user_guide/model_overview.md
    • Model documentation page added to the appropriate docs/ section
    • <model_name>.md is added to the _toc.yml

[johnjasa]

May be able to refactor this to not require total_iron_ore_produced and instead get the sum in the splitter directly. This simplifies the tech interconnections. Suggested by @dakotaramos