QUIC: Wire SSL_net_(read|write)_desired for TLS/DTLS

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21979)

ssl/ssl_lib.c

@@ -7344,11 +7344,11 @@ int SSL_net_read_desired(SSL *s)
 {
 #ifndef OPENSSL_NO_QUIC
     if (!IS_QUIC(s))
-        return 0;
+        return SSL_want_read(s);
 
     return ossl_quic_get_net_read_desired(s);
 #else
-    return 0;
+    return SSL_want_read(s);
 #endif
 }
 
@@ -7356,11 +7356,11 @@ int SSL_net_write_desired(SSL *s)
 {
 #ifndef OPENSSL_NO_QUIC
     if (!IS_QUIC(s))
-        return 0;
+        return SSL_want_write(s);
 
     return ossl_quic_get_net_write_desired(s);
 #else
-    return 0;
+    return SSL_want_write(s);
 #endif
 }