term: add an ‘id’ member to the the ‘row_uri_range’ struct

term_osc8_close() sets it from the OSC-8 ID tracked in the VT
sub-struct.

terminal.h

@@ -89,6 +89,7 @@ struct composed {
 struct row_uri_range {
     int start;
     int end;
+    uint64_t id;
     char *uri;
 };