[FRONTEND][BACKEND] Fixes for cat / reshape / addptr (#959)

Most notably, this PR:
- changes the traits (and assembly format) of addptr so it can handle offsets that have arbitrary integer width.
- adds support for `cat`

lib/Dialect/Triton/Transforms/Combine.cpp

@@ -196,7 +196,7 @@ public:
     patterns.add<CombineDotAddFRevPattern>(context);
     // %}
     patterns.add<CombineSelectMaskedLoadPattern>(context);
-    patterns.add<CombineAddPtrPattern>(context);
+    // patterns.add<CombineAddPtrPattern>(context);
     patterns.add<CombineBroadcastConstantPattern>(context);
 
     if (applyPatternsAndFoldGreedily(m, std::move(patterns)).failed())