`return_raw=true` option doesn't work with `is_async=true` router.call

[d-enk]

OK

vshard.router.callro(1, "box.info.memory", {}, {is_async=false, return_raw=true})

- msgpack.object

BUT

vshard.router.callro(1, "box.info.memory", {}, {is_async=true, return_raw=true}):wait_result()

- [{'cache': 0, 'data': 54971, 'index': 1163264, 'tx': 0, 'net': 3588096, 'lua': 11683917}]

This is unexpectedly decoded here

vshard/vshard/router/init.lua

Lines 478 to 479 in f72bb21

	local storage_ok, err
	storage_ok, res, err = res[1], res[2], res[3]

This logic needs to be propagate to is_async=true

vshard/vshard/router/init.lua

Lines 639 to 643 in f72bb21

	if do_return_raw and msgpack_is_object(storage_call_status) then
	-- Storage.call returns in the first value a flag whether user's
	-- function threw an exception or not. Need to extract it.
	-- Unfortunately, it forces to repack the rest of values into a
	-- new array. But the values themselves are not decoded.

[d-enk]

Сould get rid of repacking (copy) too...

But apparently not with this signature

vshard/vshard/storage/init.lua

Line 3144 in f72bb21

return ok, ret1, ret2, ret3

Without ret1, ret2, ...

return ok, {...}

Сould just use it:take()