geospace-code/h5fortran: New FindHDF5.cmake

Since CMake FindHDF5.cmake targets different use cases than are important for h5fortran, we created from scratch a new FindHDF5.cmake that addresses key needs including

• don't use compiler wrapper, pkg-config as these are too often broken
• test that each language links before declaring HDF5_FOUND

This allows removing numerous hacks and makes finding a working HDF5 much more robust. Please let us know if this is not finding your expected HDF5 library.