Add basic test for the AllocationTrackerClassFileTransformer

This PR adds a very basic test for the ```AllocationTrackerClassFileTransformer```. It checks
- whether classes from the tracker packer are ignored
- whether classes with the wrong prefix are ignored
- whether the byte representation of classes are changed by the transformer
or we use asm again to parse the bytecode and check if the constructor bytecode was modified. However that would make the test just mirroring whats done in the agent code.