Debugger: Introduce a pty based channel to inferiors

This is experimental for now and requires QTC_USE_PTY=1
in the environment to be used.

Change-Id: I460ce7b9283467d481e903f731f4243b7e5ec094
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@theqtcompany.com>
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/debuggerengine.h

@@ -75,6 +75,7 @@ class QmlAdapter;
 class QmlCppEngine;
 class DebuggerToolTipContext;
 class MemoryViewSetupData;
+class Terminal;
 
 struct WatchUpdateFlags
 {
@@ -352,6 +353,7 @@ protected:
     void setMasterEngine(DebuggerEngine *masterEngine);
 
     DebuggerRunControl *runControl() const;
+    Terminal *terminal() const;
 
     static QString msgStopped(const QString &reason = QString());
     static QString msgStoppedBySignal(const QString &meaning, const QString &name);