built-in option of `FromMetaTensor` in LoadImage?

[wyli]

Is your feature request related to a problem? Please describe. for backward compatibility, it might be useful to consider an option of as_dict=True to enable FromMetaTensor as part of the LoadImage transform.

Currently we have a similar design of the ensure_channel_first flag for EnsureChannelFirst https://github.com/Project-MONAI/MONAI/blob/7a5de8b7b9db101a431e70ae2aa8ea7ebb8dfffe/monai/transforms/io/array.py#L262-L263