patch 8.2.4981: it is not possible to manipulate autocommands

Problem:    It is not possible to manipulate autocommands.
Solution:   Add functions to add, get and set autocommands. (Yegappan
            Lakshmanan, closes #10291)
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 318968b..4f39ebb 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -304,6 +304,18 @@
   v9.CheckDefAndScriptFailure(['assert_report([1, 2])'], ['E1013: Argument 1: type mismatch, expected string but got list<number>', 'E1174: String required for argument 1'])
 enddef
 
+def Test_autocmd_add()
+  v9.CheckDefAndScriptFailure(['autocmd_add({})'], ['E1013: Argument 1: type mismatch, expected list<any> but got dict<unknown>', 'E1211: List required for argument 1'])
+enddef
+
+def Test_autocmd_delete()
+  v9.CheckDefAndScriptFailure(['autocmd_delete({})'], ['E1013: Argument 1: type mismatch, expected list<any> but got dict<unknown>', 'E1211: List required for argument 1'])
+enddef
+
+def Test_autocmd_get()
+  v9.CheckDefAndScriptFailure(['autocmd_get(10)'], ['E1013: Argument 1: type mismatch, expected dict<any> but got number', 'E1206: Dictionary required for argument 1'])
+enddef
+
 def Test_balloon_show()
   CheckGui
   CheckFeature balloon_eval