Description

I noticed recently that installs of xtensor/xtl go into a different directory than the one that is indicated by the HINT in OpenMCConfig.cmake.in. Namely, currently it assumes that the xtensor/xtl cmake files get installed in lib/cmake/xtensor and lib/cmake/xtensor, whereas it is actually getting installed to share/cmake/xtensor and share/cmake/xtl. Both of them seem to be common locations for installing *.cmake files, so it's hard to say what is "correct". In this PR, I've updated the find_package calls to instead give a HINT to the prefix where OpenMC was installed, which by CMake search rules will include both lib/cmake and share/cmake. It seems we've just been getting lucky in CI because everything is installed to /usr/local, which is found by other means.

A few other miscellaneous fixes in this PR:

• Fix a few typos
• Close matplotlib figures in tests to avoid a warning
• Fix a deprecated use of wwinp_to_wws in one test

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)