Decide if the session window needs to send a WINDOW_UPDATE frame
the session SessionFlowControl
number of bytes to update the session flow window with.
This verison should only be used in situations where the stream associated with the data does not exist. For example, it may have already closed and sent a RST frame.,
This must not mutate the SessionFlowControl in any way.
Decide if the stream and/or the session need a WINDOW_UPDATE frame