Associative intrinsic + tight schedule

• Adds max and min intrinsics to associative
• Adds tightness check for both associative and parallel schedules, by asserting the non-reduce arguments to the binop aren't in reduce's cycle

hercules_ir/src/ir.rs

@@ -322,7 +322,7 @@ pub enum Schedule {
     Vectorizable,
     // This reduce can be re-associated. This may lower a sequential dependency
     // chain into a reduction tree.
-    Associative,
+    TightAssociative,
 }
 
 /*