Deprecate unsupported types in operator registration

[zou3519]

We support some weird types:

import torch
lib = torch.library.Library("mylib", "FRAGMENT")
lib.define("foo(Tensor[][][][] x) -> Tensor")

PyTorch does not give full support for this type; for example, the dispatcher will just ignore x when dispatching.

We should:

1. identify an acceptable list of input/output types for custom ops and put it somewhere as the source of truth. torchgen may have this already; export has their own list: https://github.com/pytorch/pytorch/blob/main/torch/_export/serde/schema.py#L155
2. deprecate registering operators that are not of this type.

cc @ezyang @gchanan @kadeng @msaroufim @bdhirsh @anijain2305 @chauhang

[zou3519]

Hi-pri because people run into this pretty often and get confused about why it doesn't work.