build: Support running tests with address sanitizer (and use in CI)

Make possible to run tests with address sanitizer to quickly check for memory errors, although we have to disable the error exit code in case of leaks because we have some which are due to something else down in the stack (and LSAN suppression files doesn't allow to define the stack to ignore as we can in valgrind).

However, we'd abort in case of memory errors anyways, so this still helps to prevent major problems, while still logging the leaks.

In order to run pam module tests with ASAN we need to manually pass the library to LD_PRELOAD, as we do for the wrapper, thus use ldconfig in order to find its full name and check its presence.