Common tree insert function for QUIC and UDP connections. Previously, ngx_udp_rbtree_insert_value() was used for plain UDP and ngx_quic_rbtree_insert_value() was used for QUIC. Because of this it was impossible to initialize connection tree in ngx_create_listening() since this function is not aware what kind of listening it creates. Now ngx_udp_rbtree_insert_value() is used for both QUIC and UDP. To make is possible, a generic key field is added to ngx_udp_connection_t. It keeps client address for UDP and connection ID for QUIC.

--- a/src/event/quic/ngx_event_quic_socket.c
+++ b/src/event/quic/ngx_event_quic_socket.c
@@ -179,6 +179,7 @@ ngx_quic_listen(ngx_connection_t *c, ngx
 
     qsock->udp.connection = c;
     qsock->udp.node.key = ngx_crc32_long(id.data, id.len);
+    qsock->udp.key = id;
 
     ngx_rbtree_insert(&c->listening->rbtree, &qsock->udp.node);