fix(ui): propagate line wrapping state on grid_line events

This fixes the TUI's line-wrapping behavior, which was broken with the
migration to the msgpack-based UI protocol (see
https://github.com/neovim/neovim/issues/7369#issuecomment-1571812273).

src/nvim/grid_defs.h

@@ -117,6 +117,7 @@ typedef struct {
   int coloff;
   int cur_attr;
   int clear_width;
+  bool wrap;
 } GridLineEvent;
 
 #endif  // NVIM_GRID_DEFS_H