stream: add StreamExt::chunks_timeout

[jefftt]

Motivation

Closes #4694. Name is still up for suggestions!

Solution

This is essentially just adds a tokio timer on the futures_util Chunks.
Takes influence from https://github.com/mre/futures-batch which moved off the tokio timer API because it needed sub millisecond precision, however i don't think that's necessary here?

[Darksonn]

The above avoids calling wake_by_ref if both return Pending.

[Darksonn]

You will need to merge master to fix the CI failures.

[Darksonn]

I've asked for some tests below for cases I believe your code currently implements incorrectly. Would you be able to fix them and add the tests? (Or if your code is already correct, just add the test.)

[Darksonn]

The implementation looks good!

[Darksonn]

You still need to merge in master to fix the CI failures. See this page for more info.

[Darksonn]

I went though the PR again and found some more comments.

[Darksonn]

This looks good to me!

[xmakro]

@Darksonn Could you please release a new version of tokio-stream that includes this feature? Thanks!