Adding multigammaln ref and fix arange (#85153)
Partially based on https://github.com/pytorch/pytorch/pull/83662.
I'll help land this one, as Rob does not work in the PyTorch project
anymore
I removed the data-dependent check for the args, as data dependencies
are bad for many reasons (and it was failing when the input has NaNs).
It also registers arange as a decomposition, and fixes the naming of its
args.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85153
Approved by: https://github.com/mruberry, https://github.com/ngimel
