Torchscript should support union type by "|" introduced in python3.10.

[hzhangxyz]

🚀 The feature, motivation and pitch

In python3.10, we can write typing.Union[X, Y] as X | Y directly, which improves the readibility. I hope we can write it in torchscript, but currently torch.jit.script complains that Expression of type | cannot be used in a type expression

See: https://peps.python.org/pep-0604/

Alternatives

No response

Additional context

No response

### Tasks

cc @EikanWang @jgong5 @wenzhe-nrv @sanchitintel

[malfet]

TorchScript is in maintenance mode, so new feature are planned for it, but if you have a patch that enables it, please hesitate to submit one.

[tringwald]

This seems to have been added in #109293 already and works on 2.2.0 nightly builds.