src/vs/workbench/api/browser/mainThreadFileSystem.ts/MainThreadFileSystem/$copy
class MainThreadFileSystem:	$copy(source: UriComponents, target: UriComponents, opts: IFileOverwriteOptions): Promise<void> {
		return this._fileService.copy(URI.revive(source), URI.revive(target), opts.overwrite)
			.then(() => undefined).catch(MainThreadFileSystem._handleError);
	}