function _setProjectSettingsFile(settingsFile) {
        projectDirectory = FileUtils.getDirectoryPath(settingsFile);
        _toggleProjectScope();
        PreferencesImpl.projectPathLayer.setPrefFilePath(settingsFile);
        PreferencesImpl.projectStorage.setPath(settingsFile);
    }
@private

This is used internally within Brackets for the ProjectManager to signal
which file contains the project-level preferences.

@param {string} settingsFile Full path to the project's settings file