Complete PrtCnv Qt6 migration so CoPrtCnv/PrtCnvLib/PrtCnv/ddsview build

Restore dropped m_logger members, QMutex->QRecursiveMutex, splitView->split, error->errorOccurred (migration-only, verified vs legacy).

qt6-after/qt6-migrated-legatus/TetraIF/PrtCnv/PrtCnvInjectionSocket.cpp

@@ -25,6 +25,7 @@ namespace PrtCnv
 PrtCnvInjectionSocket::PrtCnvInjectionSocket()
   : m_Socket(nullptr)
   , m_Server(nullptr)
+  , m_logger(getLogger("PrtCnvInjectionSocket"))
 {}
 
 PrtCnvInjectionSocket::~PrtCnvInjectionSocket()