Move the special handling of the PKT_BIND_ACK packet from
RPCRT4_ReceiveWithAuth to RpcAssoc_BindConnection, where it belongs.

rpcrt4: Add new function RPCRT4_ReceiveWithAuth to receive a fragment and return the authentication data received, if any.

I originally implemented it on the filter but that is wrong, I will
have to fix that at a later date. It's because of
fnCaptureGraphBuilder2_FindInterface being a stub.

After seeking there might be some initial garbage, this makes it ignore it.

Fixes Valgrind warning: 'Conditional jump or move depends on
uninitialised value(s)' in metafile test.