set namespace's parent to adhoc module instead of Unknown

it's a part of the campaign to get rid of non-module roots

astroid/brain/brain_argparse.py

@@ -21,13 +21,10 @@ def infer_namespace(node, context: InferenceContext | None = None):
  "Namespace",
  lineno=node.lineno,
  col_offset=node.col_offset,
- parent=nodes.Unknown(),
+ parent=AstroidManager().adhoc_module, # this class is not real
  end_lineno=node.end_lineno,
  end_col_offset=node.end_col_offset,
  )
- # Set parent manually until ClassDef constructor fixed:
- # https://github.com/pylint-dev/astroid/issues/1490
- class_node.parent = node.parent
  for attr in set(callsite.keyword_arguments):
  fake_node = nodes.EmptyNode()
  fake_node.parent = class_node