Confirm IDs are discarded too soon

[ronkorving]

This line is problematic:

mage-sdk-unity/Mage/MessageStream/MessageStream.cs

Line 125 in d6e945d

confirmIds.Clear();

The server will keep sending those messages until confirmation has been successfully completed. I fear that the loop and its conditions around line 203 will prevent those confirm IDs from ever re-entering the confirmation list.

The behavior would be better if it replicated the JS version which only clears the confirm IDs list on a 2xx response: https://github.com/mage/message-stream.js/blob/e62d35156526204a88369d08a16a336dfff73774/http.js#L49

cc @AlmirKadric @nullorvoid