[Feature] Rename the confusing argument 'format_shape' in ActionDataPreprocessor

[makecent]

What is the problem this feature will solve?

The argument name format_shape in ActionDataPreprocessor can be misleading:

mmaction2/mmaction/models/data_preprocessors/data_preprocessor.py

Lines 30 to 37 in 4d6c934

	def __init__(self,
	mean: Optional[Sequence[Union[float, int]]] = None,
	std: Optional[Sequence[Union[float, int]]] = None,
	to_rgb: bool = False,
	to_float32: bool = True,
	blending: Optional[dict] = None,
	format_shape: str = 'NCHW') -> None:
	super().__init__()

This name is identical to Transforms.FormatShape:

mmaction2/mmaction/datasets/transforms/formatting.py

Lines 200 to 204 in 4d6c934

	@TRANSFORMS.register_module()
	class FormatShape(BaseTransform):
	"""Format final imgs shape to the given input_format.
	Required keys:

However, the context and function of these two are distinctly different. The Transforms.FormatShape is aptly named as it actively formats the shape of data. In contrast, ActionDataPreprocessor.format_shape is essentially a descriptor indicating the required shape format (i.e., 'NCHW') for the data to be correctly processed by the preprocessor.

What is the feature?

• (Option 1) A more descriptive name than ActionDataPreprocessor.format_shape, such as expected_shape_format or shape_format might better convey its purpose and reduce potential confusion.
• (Option 2) Deprecating the Transform.FormatShape and making the ActionDataPreprocessor do the shape formatting job.

What alternatives have you considered?

No response