Update tooltip texts from theoretical basis [v3.9.64]

[softwareengineerprogrammer]

Description

Addresses NREL#427: incorporate information from the theoretical basis into tooltip texts

1. Field gathering costs
2. Stimulation costs
3. End-use options: 40626ff
4. Time steps per year: c19a581
5. Exploration costs fix: d7470e0
6. OPEX
   1. a1d6700
   2. c207c18
7. Surface plant costs: e0d63ca
8. Update tooltip texts from theoretical basis [v3.9.64] #108 (comment): Update tooltip texts from theoretical basis [v3.9.64] #108 (comment)

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:

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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Originally self-reviewed in #108