Bring back KPtyProcess include

Laurent please be a bit more careful when removing includes, this
removal was causing a crash (and gcc was shouting quite a bit about it)

/home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.cpp: In member function ‘virtual void CliPlugin::processFinished(int, QProcess::ExitStatus)’:
/home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.cpp:182:9: warning: possible problem detected in invocation of ‘operator delete’ [-Wdelete-incomplete]
  182 |         delete m_process;
      |         ^~~~~~~~~~~~~~~~
/home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.cpp:182:16: warning: invalid use of incomplete type ‘class KPtyProcess’
  182 |         delete m_process;
      |                ^~~~~~~~~
In file included from /home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.h:26,
                 from /home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.cpp:23:
/home/tsdgeos/devel/kde/ark/kerfuffle/cliinterface.h:41:7: note: forward declaration of ‘class KPtyProcess’
   41 | class KPtyProcess;
      |       ^~~~~~~~~~~
/home/tsdgeos/devel/kde/ark/plugins/cliunarchiverplugin/cliplugin.cpp:182:9: note: neither the destructor nor the class-specific ‘operator delete’ will be called, even if they are declared when the class is defined
  182 |         delete m_process;
      |         ^~~~~~~~~~~~~~~~

CCMAIL: montel@kde.org