Throw std::runtime_exception instead of char*. - #9289

This should make it easier to debug exceptions falling out of the C++
code, as the C++ runtime will print the error message (the what() of
the exception) on its way to aborting the program.

Did a regex replace; removed the char* handler in CALL_CPP_FULL; and
remove a bunch of extra whitespace.

For example, before application of the patch in #9074, the failing code now gives

terminate called after throwing an instance of 'std::runtime_error'
  what():  Couldn't close file
Fatal Python error: Aborted

Should also help with #9244.

PR Summary

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way