Add an initial support of Apache::Test framework

[jajik]

This PR adds a very limited set of tests that use httpd's perl test framework. These tests are run in CI as well.

close #130

[jajik]

Worth of noting, the structure of CI will become slightly more complicated because perl-tests depend on make-with--httpd-trunk, but that imho does not matter.

The reason of this solution is that httpd in Ubuntu has a weird configuration that did not go well with the testing framework. I thought about the possibility of using fedora image but then we would have to complicate things with non-root user and switching users throughout the workflow and stuff like that. Using already built httpd with the modules seems appropriate (and we don't have to build them again as we would have for the aforementioned solutions).