Handle changing cursor shape property without creating a new profile

Using an escape sequence, e.g. printf '\e]50;CursorShape=1\a', to change
the cursor shape property like we handle DECSCUSR, i.e. as a transient
change without creating a new profile (see
SessionManager::sessionProfileCommandReceived()).

To test:
- printf '\e]50;CursorShape=1\a' to change the cursor shape, check that the
  current profile hasn't been switched to a new profile (that has no name
  as it's a temp profile)

BUG: 445590
FIXED-IN: 21.12

src/Vt102Emulation.cpp

@@ -544,6 +544,19 @@ void Vt102Emulation::processSessionAttributeRequest(int tokenSize)
         return;
     }
 
+    if (attribute == Session::ProfileChange) {
+        if (value.startsWith(QLatin1String("CursorShape="))) {
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+            const auto numStr = QStringView(value).right(1);
+#else
+            const auto numStr = value.rightRef(1);
+#endif
+            const Enum::CursorShapeEnum shape = static_cast<Enum::CursorShapeEnum>(numStr.toInt());
+            Q_EMIT setCursorStyleRequest(shape);
+            return;
+        }
+    }
+
     _pendingSessionAttributesUpdates[attribute] = value;
     _sessionAttributesUpdateTimer->start(20);
 }