Reporting more information in the diagnostics
[JENKINS-22853]

Still more diagnostics to keep track of where RemoteInvocationHandler came from.
ChunkedCommandTransport had broken the stdout evacuation.

Unlike ClassicCommandTransport, ChunkedCommandTransport wasn't
passing on the "underlying output stream", so the StandardOutputSwapper
class in Jenkins core wasn't able to evacuate fd=1.

This means if JVM writes to fd=1, for example because of a VM crash,
then we won't be able to capture that in the log output.
Instead it just corrupts the communication stream.

This whole "underlying output stream" is a hack. In the next commit
I'm going to use the channel property to fix this by using a property.
This fix is still needed because older versions of Jenkins expect the
property to return something.
A better way to expose StandardOutputStream is to use a property, not a fuzzy underlying stream.