Function check_stop_possible

test/exec/test_task.cpp:255–259

  }

  auto check_stop_possible() -> exec::task<void>
  {
    auto stop_token = co_await STDEXEC::get_stop_token();
    CHECK(stop_token.stop_possible());
  }

  TEST_CASE("task - stop token is forwarded", "[types][task]")
  {