qmlls does not work for older Qt Versions (e.g. Qt 5.15)

Currently, qmlls is unusable on Qt 5.15: there are warnings everywhere about types that could not be imported.

The reason is that qmlls uses its own QmlImportPath, and therefore analyzes the QML code using its knowledge of types that does not match the actual types available in Qt 5.15.

Find all the usages of QLibraryInfo::path(QLibraryInfo::QmlImportsPath in qmlls code and replace it with the QmlImportsPath of the Qt Kit used by the user.