[mlir] Add a TypeAttr class, allow type attributes

PiperOrigin-RevId: 207235956
diff --git a/lib/IR/AsmPrinter.cpp b/lib/IR/AsmPrinter.cpp
index 6177e19..b2ebaa6 100644
--- a/lib/IR/AsmPrinter.cpp
+++ b/lib/IR/AsmPrinter.cpp
@@ -280,6 +280,9 @@
   case Attribute::Kind::AffineMap:
     printAffineMapReference(cast<AffineMapAttr>(attr)->getValue());
     break;
+  case Attribute::Kind::Type:
+    printType(cast<TypeAttr>(attr)->getValue());
+    break;
   }
 }