Several algorithms are not applying `FWD-ENV` as they should

[ericniebler]

[jwakely]

I created https://cplusplus.github.io/LWG/issue4203 which should cover all of these

[daniel-eiband-snkeos]

Is as_awaitable another one such algorithm that doesn't handle forwarding correctly? See the use of env_of_t in awaitable-sender and in the definition of value-type of sender-awaitable. The environment of awaitable-receiver only forwards queries that satisfy forwarding-query.