Need shared (dynamic) libraries for FMS on MacOS

[srherbener]

Is your feature request related to a problem? Please describe.

When we moved to [email protected], many ctests started to fail on MacOS. We discovered that the issue was using static FMS libraries along with the Mac two-level namespace linker/loader scheme. Using shared FMS libraries (built manually) fixed this issue. For details, see: https://github.com/JCSDA-internal/fv3-jedi/issues/1237.

I submitted a PR to the NOAA-GFDL FMS repo to add in the option to build shared libraries: NOAA-GFDL/FMS#1559

I've put a workaround in place for JCSDA to get us by for now: https://github.com/JCSDA/FMS/blob/feature/mac-fms-2023.04/JEDI_BUNDLE_BUILD_ON_MACOS.md

We need to apply an equivalent patch/workaround to the build process for [email protected] when building on MacOS to hold us over until we move to whatever version of FMS will have the shared library option in the above PR.

Describe the solution you'd like

I was thinking of creating a "shared" variant that would apply a patch to have FMS build shared libraries, which would be off by default and turned on for the macos build.

Additional context
Add any other context or screenshots about the feature request here.

[eap]

We may push this feature out to 1.9: this is currently covered by a workaround. It would be nice to have this but there's enough needed for the 1.8 release.