feat(schema)!: add more range methods, rename EnumDefinition -> EnumType (#21043)

schema/type.go

@@ -1,7 +1,10 @@
 package schema
 
 // Type is an interface that all types in the schema implement.
-// Currently these are ObjectType and EnumDefinition.
+// Currently these are ObjectType and EnumType.
 type Type interface {
+	// TypeName returns the type's name.
+	TypeName() string
+
 	isType()
 }