Check memory leaks

[sylwester-zielinski]

One more thing I noticed. I was memory profiling the app using Android Studio's memory profiler to verify the memory leaks and even though ClientBleGatt was being garbage collected correctly when I used my own scope and cancelled it, ClientBleGattCallback was never garbage collected and I keep getting more and more instances with more ClientBleGatt instances. I didn't investigate further why this was happening, but I think it would be cool to check the library for memory leaks when you have some time 🙂

Originally posted by @mottljan in https://github.com/NordicSemiconductor/Kotlin-BLE-Library/issues/56#issuecomment-1789107289