Fix AXFR-style IXFR with multiple messages.

[bwelling]

The inbound xfr code is conflating the expected rdtype in responses with the incremental/replacement response style. This causes a problem when an AXFR-style IXFR response spans multiple messages, as resetting the style to AXFR (replacement) also changed the expected type in the question section of future responses to AXFR.

This change separates out the style from the expected rdtype.

This should fix #1150.

[schanzen]

Oh I see. Yes my analysis of the server response was a bit superficial.

I have another question then regarding this behavior.
As a caller, I kind of need to know if I get an AXFR response and I need to "blank slate" reset the zone information or this is an incremental update that adds/deletes the records. Is there any way to check which kind of transfer is being done?

[schanzen]

Another note:

if you change the above code to do an AXFR (serial=None) I also get an exception:

Traceback (most recent call last):
  File "/home/schanzen/dev/ascension/test.py", line 7, in <module>
    dns.query.inbound_xfr("195.43.86.175", zone, txn)
  File "/home/schanzen/dev/ascension/.venv/lib64/python3.12/site-packages/dns/query.py", line 1665, in inbound_xfr
    for _ in _inbound_xfr(txn_manager, s, query, serial, timeout, expiration):
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/schanzen/dev/ascension/.venv/lib64/python3.12/site-packages/dns/query.py", line 1470, in _inbound_xfr
    done = inbound.process_message(r)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/schanzen/dev/ascension/.venv/lib64/python3.12/site-packages/dns/xfr.py", line 207, in process_message
    raise dns.exception.FormError("unexpected origin SOA in AXFR")
dns.exception.FormError: unexpected origin SOA in AXFR