Canceled promise error for kernels without support for debugging

[jtpio]

For now we still create a new debug session even if the kernel doesn't support debugging.

After the debug session is created, we send a debugInfo message and wait for the reply on the control channel. For non-debugging kernels, this reply never comes.

Logging this as an issue so we can keep track of it and make sure the debugger doesn't interfere with regular workflows that use ipykernel.

This should be fixed by #239.