patch 8.2.4135: Vim9: ":scriptnames" shows unloaded imported autoload script

Problem:    Vim9: ":scriptnames" shows unloaded imported autoload script.
Solution:   Mark the unloaded script with "A". (closes #9552)
diff --git a/src/testdir/test_vim9_import.vim b/src/testdir/test_vim9_import.vim
index 79c1ca4..6abe478 100644
--- a/src/testdir/test_vim9_import.vim
+++ b/src/testdir/test_vim9_import.vim
@@ -1397,10 +1397,12 @@
   CheckScriptSuccess(lines)
   assert_false(exists("g:toggle_loaded"))
   assert_false(exists("g:toggle_called"))
+  assert_match('\d A: \f*[/\\]toggle.vim', execute('scriptnames'))
 
   feedkeys("tt", 'xt')
   assert_equal('yes', g:toggle_loaded)
   assert_equal('yes', g:toggle_called)
+  assert_match('\d: \f*[/\\]toggle.vim', execute('scriptnames'))
 
   feedkeys("xx", 'xt')
   assert_equal('yes', g:doit_called)