hook/mechanism to await awaitable results of fixtures/test results (asyncio/anyio/trio)

[RonnyPfannschmidt]

currently pytest plugins have to replicate a number of mechanisms to handle async fixtures

#207 was originally intended to help with that, but was more broad than necessary

with #7337 being soon integrated, the interface should be narrowed and coordinated with the asyncio/trio/curio plugins

[Zac-HD]

As a maintainer of pytest, trio, anyio, and pytest-trio (anyio has the pytest plugin built-in), I think the status quo is working pretty well. Anything else we need to do before closing this?

[RonnyPfannschmidt]

We absolutely should upstream a part of it

I want to be in a position where nextitemcan be removed from the runtest protocol