[nla,transport] move public key retrieval to transport IO.

include/freerdp/transport_io.h

@@ -41,6 +41,8 @@ extern "C"
 	typedef BOOL (*pTransportAttach)(rdpTransport* transport, int sockfd);
 	typedef int (*pTransportRWFkt)(rdpTransport* transport, wStream* s);
 	typedef SSIZE_T (*pTransportRead)(rdpTransport* transport, BYTE* data, size_t bytes);
+	typedef BOOL (*pTransportGetPublicKey)(rdpTransport* transport, const BYTE** data,
+	                                       DWORD* length);
 
 	struct rdp_transport_io
 	{
@@ -52,6 +54,7 @@ extern "C"
 		pTransportRWFkt ReadPdu;  /* Reads a whole PDU from the transport */
 		pTransportRWFkt WritePdu; /* Writes a whole PDU to the transport */
 		pTransportRead ReadBytes; /* Reads up to a requested amount of bytes from the transport */
+		pTransportGetPublicKey GetPublicKey;
 	};
 	typedef struct rdp_transport_io rdpTransportIo;