bpo-36763: Implement PyWideStringList_Insert() of PEP 587 (GH-15423)

(cherry picked from commit 3842f2997fbd4dc840986aad2bb94656815e243b)

Co-authored-by: Victor Stinner <vstinner@redhat.com>
diff --git a/Programs/_testembed.c b/Programs/_testembed.c
index 3d27ed2..3873009 100644
--- a/Programs/_testembed.c
+++ b/Programs/_testembed.c
@@ -1350,8 +1350,14 @@
         goto fail;
     }
 
+    status = PyWideStringList_Insert(&config.module_search_paths,
+                                     1, L"test_path_insert1");
+    if (PyStatus_Exception(status)) {
+        goto fail;
+    }
+
     status = PyWideStringList_Append(&config.module_search_paths,
-                                     L"init_read_set_path");
+                                     L"test_path_append");
     if (PyStatus_Exception(status)) {
         goto fail;
     }