Summary: When we send a reliable reset, we don't want to reset the entire `writeBuffer`, `retransmissionBuffer`, `lossBuffer`, and `pendingWrites`. We only want to reset them up to the `reliableSize`. I'm making helper functions to do this.
Reviewed By: jbeshay
Differential Revision: D64907982
fbshipit-source-id: ad9256638f5e0cb5f7c038e2c9d12253a7776b2d