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
looking into the content is really tying the test to what it does. also you would have to deal with any "magic rewrites" asm does (and we might not care about). What might be a sensible test is to test that the actual byte array is larger, because we know it needs to contain extra instructions.
We maybe want to scan for our tracker class name because it should be in there (due to invokestatic)