_linalg_qr_helper meta function
Taken from https://github.com/albanD/subclass_zoo/blob/main/python_meta_tensor.py
Signed-off-by: Edward Z. Yang <ezyangfb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78603
Approved by: https://github.com/Lezcano, https://github.com/mruberry
