Consider absolute file paths for .qmlproject

Since .qmlproject does not support qrc files we might consider packaging a certain directory to a .rcc. Qmlscene then needs to be able to load .rcc files.

This is fully optional and the .rcc should only contain images and similar resources.
Using a .rcc file would allow supporting absolute file paths for resued assets like e.g. iso icons.
People that prefer absolute file paths are happy.

There would be no .qrc file. Creating the .rcc would be managed by the qmlproject manager.