Expose QUrl::toLocalFile() to Julia

[rakeshksr]

Currently, QUrl::toLocalFile() from Qt is not exposed in the Julia bindings while QUrl::fromLocalFile exposed.

When a user selects a file via a QML based file picker or drag-and-drop interface, the returned object is often a QUrl. To use this file in Julia we need the raw local path.

Current Workaround:

On Qml side

function toLocalFile(url) {
    return decodeURIComponent(url).replace(/^(file:\/{2,3})/, "");
}

julia_path = toLocalFile(qurl)
Julia.operationOnJuliaSide(julia_path)

[barche]

This would be easy to add, but I think it would be more efficient to use the URIs.jl package for this?

[rakeshksr]

I am able to decode the path successfully with URIs.jl; however, I am unable to properly handle the file prefix. On Windows, QML returns a URI in the format file:///path, whereas on other platforms it returns file://path.

I would prefer not to introduce an additional dependency for functionality that is already supported by this library.