fix: macOS rpath and dynamic library issues

[c-dilks]

• Add macOS CI tests, since many of our users work on macOS (though high-statistics processing will likely be on Linux machines).
• Fix python bindings don't work on macOS #75
• Fix macOS rpath is not defined correctly #71

[c-dilks]

BSD vs. Linux commands are going to make this fun...

[c-dilks]

Successfully reproduced #71

https://github.com/JeffersonLab/iguana/actions/runs/7427660531/job/20213801254#step:11:9

[c-dilks]

Needed rpaths depend on platform:

• on Linux, we need both hipo4 and iguana in the rpath
• on macOS, we need just hipo4 (but bindings may need iguana, as indicated by the failing python test)

Considering #23, but iguana isn't the only consumer.

We may need to figure out how to set multiple rpath entries on macOS, since it appears to be different than Linux. However, no responses to mesonbuild/meson#5760 may mean multiple rpaths is not the right approach to solving this issue (and no, I don't want to force users to set $LD_LIBRARY_PATH or $DYLD_LIBRARYPATH).

[c-dilks]

We may need to figure out how to set multiple rpath entries on macOS, since it appears to be different than Linux.

Running install_name_tool -add_rpath post-installation on macOS executables is a workaround, but not a nice one. See cb14708

[c-dilks]

I can't figure out how to get Python bindings to work on macOS, so disabling that test for now and deferring to #75

[c-dilks]

I can't figure out how to get Python bindings to work on macOS, so disabling that test for now and deferring to #75

Now resolved by this PR.