[mlir][transform] Fix merge_handle asm format

[Dinistro]

Summary

This commit ensures that the merge_handles operation prints its
deduplicate attribute as an optional keyword instead of "unit".

mlir/include/mlir/Dialect/Transform/IR/TransformOps.td

let description = [{
     and so on. If `deduplicate` is set, do not add the given Payload IR
     operation more than once to the final list regardless of it coming from the
     same or different handles. Consumes the operands and produces a new handle.
   }];
 
   let arguments = (ins Variadic<TransformHandleTypeInterface>:$handles,
                        UnitAttr:$deduplicate);
   let results = (outs TransformHandleTypeInterface:$result);
-  let assemblyFormat = "($deduplicate^)? $handles attr-dict `:` type($result)";
+  let assemblyFormat = "(`deduplicate` $deduplicate^)? $handles attr-dict `:` type($result)";
   let hasFolder = 1;
 }
 
 def NamedSequenceOp : TransformDialectOp<"named_sequence",
     [CallableOpInterface,
      FunctionOpInterface,
      IsolatedFromAbove,
      DeclareOpInterfaceMethods<MemoryEffectsOpInterface>,

mlir/test/Dialect/Transform/test-interpreter.mlir

^bb0(%arg1: !transform.any_op):
     %1 = pdl_match @subi in %arg1 : (!transform.any_op) -> !transform.any_op
     %2 = merge_handles %0, %1 : !transform.any_op
     test_print_remark_at_operand %2, "matched" : !transform.any_op
   }
 }
 
 // -----
 
+func.func @foo(%arg0: index) {
+  %0 = arith.addi %arg0, %arg0 : index
+  return
+}
+
+transform.with_pdl_patterns {
+^bb0(%arg0: !transform.any_op):
+  pdl.pattern @addi : benefit(1) {
+    %0 = pdl.operands
+    %1 = pdl.types
+    %2 = pdl.operation "arith.addi"(%0 : !pdl.range<value>) -> (%1 : !pdl.range<type>)
+    pdl.rewrite %2 with "transform.dialect"
+  }
+
+  transform.sequence %arg0 : !transform.any_op failures(propagate) {
+  ^bb0(%arg1: !transform.any_op):
+    %0 = pdl_match @addi in %arg1 : (!transform.any_op) -> !transform.any_op
+    %1 = pdl_match @addi in %arg1 : (!transform.any_op) -> !transform.any_op
+    %2 = merge_handles deduplicate %0, %1 : !transform.any_op
+    // expected-remark @below {{1}}
+    test_print_number_of_associated_payload_ir_ops %2 : !transform.any_op
+  }
+}
+
+// -----
+
 func.func @foo() {
   "op" () { target_me } : () -> ()
   // expected-note @below {{when applied to this op}}
   "op" () : () -> ()
   return
 }
 
 transform.with_pdl_patterns {