Adapt tests' execution to relevant OS only

[Toparvion]

Some tests in AnaLog are platform dependent, for example those for checking symlink resolution of Log Access Guard.
Such tests must take in count current OS and be capable to exclude/include some check basing on it.

As a consequence, the tests must be run in several environments, ideally in Linux, macOS and Windows. This can be achieved with recently introduced Travis CI integration (see its documentation).

[Toparvion]

From the tests' point of view, the corresponding separation can be achieved by leveraging JUnit's org.junit.jupiter.api.condition.EnabledOnOs conditional annotation (see the doc).