For jcsda_emc_spack_stack: bug fix in gsibec package: sp is a runtime dependency

[climbfuji]

Description

I am fixing this on develop instead of release/1.7.0, we'll simply work around this by instructing people to load the sp module manually when using gsibec.

Make sp a runtime dependency, and also put comments in place for future transition to ip (see https://github.com/GEOS-ESM/GSIbec/issues/65 and https://github.com/GEOS-ESM/GSIbec/pull/66).

Issue(s) addressed

n/a

Dependencies

n/a

Impact

n/a

Checklist

• [x] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have run the unit tests before creating the PR

[climbfuji]

@AlexanderRichert-NOAA This can be merged anytime