patch 8.2.4911: the mode #defines are not clearly named

Problem:    The mode #defines are not clearly named.
Solution:   Prepend MODE_.  Renumber them to put the mapped modes first.
diff --git a/src/drawline.c b/src/drawline.c
index 679e4ca..caff9ab 100644
--- a/src/drawline.c
+++ b/src/drawline.c
@@ -1963,7 +1963,7 @@
 			// In Insert mode only highlight a word that
 			// doesn't touch the cursor.
 			if (spell_hlf != HLF_COUNT
-				&& (State & INSERT) != 0
+				&& (State & MODE_INSERT)
 				&& wp->w_cursor.lnum == lnum
 				&& wp->w_cursor.col >=
 						    (colnr_T)(prev_ptr - line)
@@ -2595,7 +2595,7 @@
 	if (p_imst == IM_ON_THE_SPOT
 		&& xic != NULL
 		&& lnum == wp->w_cursor.lnum
-		&& (State & INSERT)
+		&& (State & MODE_INSERT)
 		&& !p_imdisable
 		&& im_is_preediting()
 		&& draw_state == WL_LINE)