The audio file list in <audioFileInfoList>.
The files, one <audioFileInfo> each; the firmware reads up to 32.
optional
item: AudioFileInfoListLegacyItem[]
The files as the RLC-823A writes them in its cmd 347 reply, one <item>
each. RLC-823A only; absent when there are none.
optional
maxFileNumber: number
How many files the doorbell can hold; cmd 347 reply only, always 12.