A persistence strategy which saves files to the local file system.
AssetStorageStrategy((reqest: Request, identifier: string) => string) | undefined(fileName: string, data: ReadStream, encoding?: BufferEncoding | null) => Promise<string>(fileName: string, data: Buffer) => Promise<string>(fileName: string) => Promise<boolean>(identifier: string) => Promise<Buffer>(identifier: string, encoding?: BufferEncoding | null) => Promise<Stream>(identifier: string) => Promise<void>