Use an enumerated type for asset types instead of lowercase strings

[Deleted user]

The tab system used on profile pages may change in the future and using lowercase strings corresponding to the tab names isn't a very good idea anyway; it would be preferable, as you yourself suggested, to use an enumerated type that contains all the asset types (even those that information cannot be gained about from profiles; the relevant function will just throw an error when those are used, but they can be used in other functions).

The values of the enumerator for each type should be the asset type identifier; the enum npm package makes it possible to customize the enumerator value and the list of all asset type identifiers is available on the wiki.

[matthewdean]

Done.