Add a binary (byte-transparent) character set and fix ECI value resolution

Add a binary (byte-transparent) character set and fix ECI value resolution: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Our character-set / ECI machinery is used to translate raw barcode payload bytes into Unicode and back. Two things are missing/wrong today.