patch 9.0.0423: "for" and "while" not recognized after :vim9cmd and :legacy

Problem:    "for" and "while" not recognized after :vim9cmd and :legacy.
            (Emanuele Torre)
Solution:   Recognize all the command modifiers. (closes #11087)
            Add a test to check the list of modifiers.
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index dbda7e1..d7abcb5 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -87,6 +87,7 @@
 	test_clientserver \
 	test_close_count \
 	test_cmdline \
+	test_cmdmods \
 	test_cmdwin \
 	test_command_count \
 	test_comments \
@@ -346,6 +347,7 @@
 	test_clientserver.res \
 	test_close_count.res \
 	test_cmdline.res \
+	test_cmdmods.res \
 	test_cmdwin.res \
 	test_command_count.res \
 	test_comments.res \