Coroutine awaitables

The second part of the support is provided by header <outcome/coroutine_support.hpp> (or <outcome/experimental/coroutine_support.hpp> if you want Coroutine support for Experimental Outcome). This adds into namespace OUTCOME_V2_NAMESPACE::awaitables (or OUTCOME_V2_NAMESPACE::experimental::awaitables) these awaitable types suitable for returning from a Coroutinised function: eager<T, Executor = void> An eagerly evaluated Coroutine: invoking co_await upon a function returning one of these immediately begins the execution of the function now. If the function never suspends, the overhead is similar to calling an ordinary function. »