patch 8.2.2806: Vim9: using "++nr" as a command might not work

Problem:    Vim9: using "++nr" as a command might not work.
Solution:   Do not recognize "++" and "--" in a following line as addition or
            subtraction.
diff --git a/src/ex_cmdidxs.h b/src/ex_cmdidxs.h
index 0d148d7..2696128 100644
--- a/src/ex_cmdidxs.h
+++ b/src/ex_cmdidxs.h
@@ -69,4 +69,4 @@
   /* z */ {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 }
 };
 
-static const int command_count = 577;
+static const int command_count = 579;