Make bitwise_left_shift/right_shift scalar variants composite
They are written in a totally generic way. This makes meta
tensors work on them.
Signed-off-by: Edward Z. Yang <ezyangfb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74317
Approved by: https://github.com/ngimel, https://github.com/bdhirsh
