Supporting ModuleFiles nodes in QmlProjectItem

There's a simple implementation of supporting multiple qmlproject files in QmlProjectManager. But this integration is missing the context information about the sub-qmlproject files which can lead to unexpected issues or unwanted side effects.

Better implementation would be adding proper converters, tests and public getters/setters in QmlProjectItem by parsing and interpreting ModuleFiles nodes.

Here's an example of this node;

ModuleFiles {
        files: [
            "imports/KMCStyle/KMCStyle.qmlproject",
            "imports/subproject2/subproj2.qmlproject"
        ]
        // Uncomment for adding Qul modules
        MCU.qulModules: [
            // "Qul::Controls",
            // "Qul::ControlsTemplates",
            // "Qul::Shapes",
            // "Qul::Timeline"
        ]
    } 

Acceptance criteria:

• Convert qmlproject to their json format
• Get list of qmlprojects using a functions
• Auto tests