[mlir][td] Rename pack_paddings in structured.pad (#111036)

The pack_paddings attribute in the structure.pad TD Op is used to set
the `nofold` attribute in the generated tensor.pad Op. The current name
is confusing and suggests that there's a relation with the tensor.pack
Op. This patch renames it as `nofold_flags` to better match the actual
usage.

Author: banach-space

mlir/python/mlir/dialects/transform/structured.py

@@ -377,7 +377,7 @@ def __init__(
         pad_to_multiple_of: Optional[Union[DynamicIndexList, ArrayAttr]] = None,
         padding_values: Optional[Union[ArrayAttr, Sequence[Attribute]]] = None,
         padding_dimensions: OptionalIntList = None,
-        pack_paddings: OptionalIntList = None,
+        nofold_flags: OptionalIntList = None,
         transpose_paddings: Optional[
             Union[ArrayAttr, Sequence[Union[ArrayAttr, IntOrAttrList]]]
         ] = None,
@@ -407,7 +407,7 @@ def __init__(
             padding_values=padding_values,
             padding_dimensions=padding_dimensions,
             static_pad_to_multiple_of=static_pad_to_multiple_of,
-            pack_paddings=pack_paddings,
+            nofold_flags=nofold_flags,
             transpose_paddings=transpose_paddings,
             copy_back_op=copy_back_op,
             loc=loc,