GDA-5479 (master-->8.34) Move OutputStream methods from JythonServer into an inner class

This means JythonServer no longer needs to extend OutputStream.
GDA-5479 (master-->8.34) Add write(String) method to Terminal interface so terminal output can be passed as a String

Also update Terminal implementations in uk.ac.gda.{core,client}
GDA-5479 (master-->8.34) Allow JythonServer to receive terminal output through a Writer instead of an OutputStream
GDA-5479 (master-->8.34) Jython displayhook should not convert PyUnicode objects if a writer is being used

A PyUnicode string is perfectly fine as it is, and should just go straight to
the terminal without being converted to a PyString.
Merge remote branch 'remotes/origin/gda-5479'