[Quantization] support pass MappingType for TorchAoConfig

[a120092009]

What does this PR do?

Passing MappingType for TorchAoConfig is invalid

  File "/workspace/volume/zty/diffusers/src/diffusers/configuration_utils.py", line 123, in register_to_config
    logger.debug(f"Updating config from {previous_dict} to {internal_dict}")
                                                           ^^^^^^^^^^^^^^^
  File "/workspace/volume/zty/diffusers/src/diffusers/quantizers/quantization_config.py", line 671, in __repr__
    return f"{self.__class__.__name__} {json.dumps(config_dict, indent=2, sort_keys=True)}\n"
                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/json/__init__.py", line 238, in dumps
    **kw).encode(obj)
          ^^^^^^^^^^^
  File "/usr/lib/python3.12/json/encoder.py", line 202, in encode
    chunks = list(chunks)
             ^^^^^^^^^^^^
  File "/usr/lib/python3.12/json/encoder.py", line 432, in _iterencode
    yield from _iterencode_dict(o, _current_indent_level)
  File "/usr/lib/python3.12/json/encoder.py", line 406, in _iterencode_dict
    yield from chunks
  File "/usr/lib/python3.12/json/encoder.py", line 406, in _iterencode_dict
    yield from chunks
  File "/usr/lib/python3.12/json/encoder.py", line 439, in _iterencode
    o = _default(o)
        ^^^^^^^^^^^
  File "/usr/lib/python3.12/json/encoder.py", line 180, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type MappingType is not JSON serializable

Add JSON encoder for supporting MappingType

Test result:

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[a120092009]

@a-r-r-o-w @dacorvo Could you guys take a look, thx :)

[a-r-r-o-w]

@bot /style

[github-actions]

Style fixes have been applied. View the workflow run here.

[a-r-r-o-w]

Thank you!

[a-r-r-o-w]

The update test is passing for me locally, thanks!