QmlDesigner: Add AsynchronousImageFactory

Task-number: QDS-5861
Change-Id: I3d938b3ddaa965da2105a326ea68f498dbb60fa0
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/libs/sqlite/sqlitetimestamp.h

@@ -40,6 +40,12 @@ public:
         return first.value == second.value;
     }
 
+    friend bool operator!=(TimeStamp first, TimeStamp second) { return !(first == second); }
+
+    bool isValid() const { return value >= 0; }
+
+    long long operator*() { return value; }
+
 public:
     long long value = -1;
 };