ports build integration and spiner install cleanup

[Yurlungur]

PR Summary

This is a follow up to the work in ports-of-call. Here I:

• add a spackage for ports-of-call into the local spiner spack repo
• update spiner's cmake build system to look for an external ports-of-call package and use it if available
• fix some errors in the spackage in spiner
• have spiner output package config information for cmake so that downstream codes can FindPackage for it more easily.

In the process, I changed spiner from providing two targets: spiner::flags and spiner::libs to just providing spiner::spiner. In this case, I believe this was less cumbersome and produced a lot less cmake code.

PR Checklist

• Code is formatted.
• Adds a test for any bugs fixed. Adds tests for new features.

[Yurlungur]

As I am not super confident in my cmake skills, a cmake wizard should probably look over this. @mauneyc-LANL @junghans feedback welcome.

[Yurlungur]

@dholladay00 @mauneyc-LANL I believe all comments have been addressed. Want to take a look?

[mauneyc-LANL]

@dholladay00 @mauneyc-LANL I believe all comments have been addressed. Want to take a look?

looks good to me.

[Yurlungur]

@dholladay00 @mauneyc-LANL I believe all comments have been addressed. Want to take a look?

looks good to me.

Can you click approve?