OutputStreamLogDispatcher

Dispatcher of STDOUT vs STDIN output to SLF4j logger levels.

This allows to customize a ManagedProcess' default behavior of sending STDOUT to INFO and STDERR to ERROR. In particular, this can be used to tune "noisy" processes which output too much stuff to STDERR which isn't really meant for an error log in a Java application, by filtering based on actual output line content (useful e.g. if the process uses its own text to distinguish log levels in it's output).

It also allows to suppress logging (some) STDOUT and/or STDERR all together, by permitting to return null. This is useful e.g. for processes which emit some lines you might never want to see in any log at all, e.g. for security.