potential issue with large reads on nonframed messages

In tracking down an issue in an unrelated codebase, I discovered that at least in some cases, passing more than 2GiB to the pyca/cryptography `Cipher.update()` methods can cause issues with the underlying OpenSSL implementation.

This is not an issue with framed messages because our max frame size is 2GiB, but could be an issue for nonframed messages larger than 2GiB.

We should add tests that check for this edge case, and if it is an issue we can add chunking logic.

首先，通过将超过 2GiB 的数据传递给非分帧消息的 pyca/cryptography Cipher.update() 方法来复现已报告的行为，并将其与分帧消息进行比较。为该边界情况添加回归测试；完成的标准是大型非分帧消息能够可靠工作，并在确认底层 OpenSSL 问题后添加分块逻辑。

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