[GUFA] Prepare for cone types [NFC] (#5086)

This does not actually add cone types, but it does NFC refactoring towards that.
Specifically it replaces the internal ExactType with ConeType, and the latter
has a depth, so a cone type of depth 0 is the old exact type.

Cone types with depth > 0 are not possible yet, keeping this NFC.

I believe this design with a depth for cone types has little overhead. It does add
to the size of ConeType, but the variant there is larger anyhow (it contains a
Literal). And things like isSubType need to loop anyhow, so looping up to the
depth etc. in checks won't make things slower. 

0 files changed, 0 insertions, 0 deletions