[NFC] Make Type a class instead of enum (#2433)

The plan is to extend `Type` to represent arbitrary multivalue types,
and as a prerequisite for that it is necessary to make it a class
instead of an enum. This PR bends over backwards to add all the
automatic conversions and constants necessary to allow the rest of the
code to compile unmodified, but in the future it should be possible to
standardize usage across the code base and remove some of these
utilities.

0 files changed, 0 insertions, 0 deletions