Qml2Puppet: Support mocking `Application`/`Qt.application` properties

See:

• https://doc.qt.io/qt-6/qml-qtquick-application.html
• https://doc.qt.io/qt-6/qml-qtqml-qt.html#application-prop

The Application singleton (or the Qt.application object) allows properties to be passed from from C++ to QML (e.g. QCoreApplication::setApplicationName(), QGuiApplication::setFont())

In the user's application, the following code would show the name, version, and font that were set in QGuiApplication:

Text {
	text: `${Qt.application.name} (${Qt.application.version})`
	font.family: Qt.application.font.family
	font.pixelSize: Qt.application.font.pixelSize
}

However, inside Qt Design Studio, the 2D view and the Live Preview would show something like "Qml2Puppet (4.3.1.0)" in default system font.

It would be useful if users had a way to pass such information to qml2puppet. (Perhaps new fields in the *.qmlproject file?)