Utils: Move ProcessArgs class into filepair of its own

There's not much interaction between ProcessArgs and QtcProcess
and both .cpp are still quite big, with non-trivial bits.

Change-Id: Id84202f6c34057bf87cc8f27fbb45f78f105e9a5
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/ssh/sftpsession.cpp

@@ -30,8 +30,8 @@
 #include "sshsettings.h"
 
 #include <utils/fileutils.h>
+#include <utils/processargs.h>
 #include <utils/qtcassert.h>
-#include <utils/qtcprocess.h>
 
 #include <QByteArrayList>
 #include <QFileInfo>