Replace _dtype_default_type_hack (#81479)
Currently any function with a default dtype other than None has to be
manually entered into this function. Instead, this reads the default
directly from `native_functions.yaml`. In order to do this, I also
change `PythonSignatureGroup` to take `tensor_options_args` from the
functional variant since the out variant doesn't actually have tensor
options arguments to take the default values from.
Also note that we need to use `default_init` instead of `default`
because the out argument version doesn't have a `tensor_options`
argument to extract the default value from and so the PythonSignature
objects wouldn't match.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81479
Approved by: https://github.com/albanD
