create aux-info-types.csv to capture different aux info types

[podborski]

mp4ra does not currently have a dedicated registration table for aux_info_type values

creating this issue to keep track of this

stai, sample auxiliary information Aux_Info_Type,UNCV

cenc
cbc1
cens
cbcs
sve1

[podborski]

'suid' – Identifies an aux_info_type for sample auxiliary information in a file conformant to NGA.STND.0076-01_V1.0.0_GIMI. The 'suid' aux_info_type indicates the carriage of universally unique Content Identifiers for each sample in a track.

from #298

[podborski]

The CENC spec also defines that aux_info_type can default to the item_type of the referring item (for non-protected items). So the namespace of aux_info_type values overlaps with scheme codes and potentially item types.

This is important to decide how to structure the CSV (e.g., whether to include a column indicating which spec defines the aux_info_type format, or a "type" column distinguishing encryption vs. metadata uses).