Renaming DOE to parameter sweep throughout

[johnjasa]

Rename design_of_experiments to parameter_sweep and improve docs

Renames the design_of_experiments YAML key and all related references to parameter_sweep throughout the codebase to avoid confusion with "Department of Energy" (DOE), which is frequently referenced in our domain.

The core code in pose_optimization.py supports both the new parameter_sweep key and the legacy design_of_experiments key for backward compatibility.

Additional documentation improvements:

• Added short descriptions for each generator type (uniform, fullfact, plackettburman, boxbehnken, latinhypercube, csvgen)
• Added a note explaining the relationship to OpenMDAO's "Design of Experiments" terminology

Originally suggested by James Niffenegger.

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:

• Rename design_of_experiments to parameter_sweep in core Python code with backward compatibility
• Update all YAML driver configs and example files
• Update tests
• Rewrite docs page and rename file
• Update cross-references in other doc pages
• Add generator type descriptions
• Update run-cases docs to recommend parameter sweeps

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
  • At least one complete sentence has been provided to describe the changes made in this PR
  • After the above, a hyperlink has been provided to the PR using the following format:
    "A complete thought. [PR XYZ]((https://github.com/NatLabRockies/H2Integrate/pull/XYZ)", where
    XYZ should be replaced with the actual number.

Section 4: Related Issues

User feedback that "DOE" as an acronym is confusing with "Department of Energy" in the energy systems domain.

Section 5: Impacted Areas of the Software

Section 5.1: New Files

• docs/user_guide/parameter_sweep_in_h2i.md
  • Replaces design_of_experiments_in_h2i.md with updated terminology, generator descriptions, and improved formatting.

Section 5.2: Modified Files

Anywhere we had design of experiments listed explicitly has parameter sweep now.
Some examples still say "doe", which I think is fine, but let me know if you disagree!

Section 6: Additional Supporting Information

The legacy design_of_experiments YAML key is still supported for backward compatibility. Existing configs will continue to work without changes, but new configs should use parameter_sweep.