src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts/SimpleFileDialog/createBackItem
class SimpleFileDialog:	private async createBackItem(currFolder: URI): Promise<FileQuickPickItem | undefined> {
		const fileRepresentationCurr = this.currentFolder.with({ scheme: Schemas.file, authority: '' });
		const fileRepresentationParent = resources.dirname(fileRepresentationCurr);
		if (!resources.isEqual(fileRepresentationCurr, fileRepresentationParent)) {
			const parentFolder = resources.dirname(currFolder);
			if (await this.fileService.exists(parentFolder)) {
				return { label: '..', uri: resources.addTrailingPathSeparator(parentFolder, this.separator), isFolder: true };
			}
		}
		return undefined;
	}