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/core/ngx_connection.c
+++ b/src/core/ngx_connection.c
@@ -72,6 +72,10 @@ ngx_create_listening(ngx_conf_t *cf, str
 
     ngx_memcpy(ls->addr_text.data, text, len);
 
+#if !(NGX_WIN32)
+    ngx_rbtree_init(&ls->rbtree, &ls->sentinel, ngx_udp_rbtree_insert_value);
+#endif
+
     ls->fd = (ngx_socket_t) -1;
     ls->type = SOCK_STREAM;