hitting 'resend' on queued messages can still send in the wrong order

[ara4n]

i'm on bad connectivity on a train. i sent 4 messages in a row. the first and fourth(?!) entered error state; the 2nd and 3rd were still pending. I hit retry to resend the failed ones; they end up sending in order 4,2,3,1. It feels like we should serialise the message sending so that the ordering is preserved and ensure that if one message gets stuck, it blocks subsequent ones, to avoid this miserable failure mode

[ara4n]

see also #22885

[Johennes]

I'm upgrading this to S-Major. For one thing, this is part of what we've identified as "Chronic Issues". For another, sending messages appears to be critical functionality to me and manually re-queuing them in the correct order doesn't feel like a satisfactory workaround to me (especially since by the time you realize they were send in the wrong order, the damage is already done).