patch 8.2.4005: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/dict.c b/src/dict.c
index f39be72..64c9d5f 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -1116,7 +1116,7 @@
 	    }
 	    else if (*action == 'e')
 	    {
-		semsg(_("E737: Key already exists: %s"), hi2->hi_key);
+		semsg(_(e_key_already_exists_str), hi2->hi_key);
 		break;
 	    }
 	    else if (*action == 'f' && HI2DI(hi2) != di1)