Use official source for FileFormat

[markbrough]

Would it make sense to switch out the FileFormat codelist in favour of the official one?

Current version from datasets:
https://github.com/datasets/media-types/blob/master/media-types.csv

Official version from IANA:
https://www.iana.org/assignments/media-types/media-types.xhtml

It's available as a CSV download (for each category, e.g. application):
https://www.iana.org/assignments/media-types/application.csv

or as XML for the full set:
https://www.iana.org/assignments/media-types/media-types.xml

However, I noticed in both places (both the datasets version and the IANA version) the names are a bit messy, e.g. including the word OBSOLETE in a bunch of places. I guess we could parse that reasonably easily to catch the withdrawn codes?

[andylolz]

Good point(s)! I’ve split this into two tickets (see: #8).