Add Total CAPEX ($/kW) output for SAM-EM in summary of results category [v3.11.17]

[softwareengineerprogrammer]

Description

1. Implements Add $/kW result metric NatLabRockies/GEOPHIRES-X#391

Testing & Verification

1. Unit tests added: N/A
2. Unit tests updated: Affected SAM-EM examples regenerated
3. Manual testing
   1. Web interface:

TODO

1. Regen FPC5 so sensitivity results have total capex/kW (without having to rerun in web interface)

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Change Checklist:

Observe the following checklist items if your change includes a new version (see versioning notes and version management docs).

Before merging:

1. Add a CHANGELOG entry (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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Self-reviewed in #138