Add a correctness check for C++ types to custom operators (#15247)

Add a correctness check for C++ types to custom operators (#15247)

Summary:
The JIT uses `int64_t` for its integer type and `double` for its floating point type, but users quite often want to write `int` or `float` and that currently fails in not-so-nice ways for custom ops. This PR adds a simple `static_assert` to catch these common failure cases.

zdevito
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15247

Differential Revision: D13493941

Pulled By: goldsborough

fbshipit-source-id: c1cd0d10ab5838c75f167c0bdb57e45a0bc1344e