Implements: AE-1959

LibreOffice prints out warning to stderr on newer MacOS versions. The
warning doesn't seem to be anything serious, and there doesn't seem to
be any solutions for it available. Exit code is still checked for
errors.

Create a service for Palveluväylä to make the codebase a bit clearer.
Separate parsing languages into a function. Clean up the test code a
bit. Comment language discrimination in pdf search.