Provide proper API for test-framework specific behavior

[skuzzle]

There are currently two known places where we depend on the behavior of actual test framework being used:

• AssumptionExceptionDetector tries to detect the propert assumption exception
• StaticOrphanedSnapshotDetector tries to identifiy whether a method contains a snapshot assertionn which only works for JUnit5 tests with Snapshot parameter

Since version 1.8.0 we're shipping test-framework specific artifacts. So it would just be natural to move this logic into the respective artifacts to have the core fully framework-agnostic.