Have pretty-printer truncate types if their argument list is really long

[dgrnbrg]

Enums, unions, and bundles can have extremely complicated schemas. These should be elided w/ ellipsis by the pretty printer, because they rarely are of much interest beyond their kind, especially since very long ones obscure the actual data. Huge types are very common in piplin code, because they might represent the union of several structs, each of which contains at least one enum.