[WIP] FGEM Integration

[softwareengineerprogrammer]

Description

Describe your change, including links to relevant tracking issue(s), implementation approach, new/updated documentation,
and any other relevant information.

Testing & Verification

1. Unit tests added: Describe new unit tests added, if any.
2. Unit tests updated: Describe existing unit tests that were updated, if any.
3. Manual testing: Describe any additional manual testing steps that were performed, such as running the change on a pre-existing data set you own.

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Change Checklist

Observe the following checklist items before and after merging, as applicable.

Before merging:

1. I certify that I am a human and I have manually verified the correctness of the changes in this PR.
2. Add a CHANGELOG entry if your change includes a new version¹ (example). RST Template:

M.m.P: `TITLE <https://github.com/NREL/GEOPHIRES-X/pull/PR-NUMBER>`__ | `release <https://github.com/NREL/GEOPHIRES-X/releases/tag/vM.m.P>`__

After merging:

1. Push tag(s) to GitHub: git push origin refs/tags/vM.m.P
2. Post a change announcement to the GEOPHIRES Change Announcements Discussion (example). Markdown template:

M.m.p: [TITLE](https://github.com/NREL/GEOPHIRES-X/pull/PR-NUMBER) | [release](https://github.com/NREL/GEOPHIRES-X/releases/tag/vM.m.P)

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Additional metadata such as TODO items or link to your initial self-review (PR into your own fork created prior to submission)

Footnotes

1. See versioning notes and version management docs. ↩