tests/test-runner: Plumb "resize" command

The test client could already understand the resize command, but they
could not be added to metatests as the command was not properly plumbed
via the test runner. Establish the plumbing for the resize command so
that resize tests can be added.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1171

src/tests/test-runner.c

@@ -504,6 +504,20 @@ test_case_do (TestCase *test,
 
       test_client_wait_for_window_shown (client, window);
     }
+  else if (strcmp (argv[0], "resize") == 0)
+    {
+      if (argc != 4)
+        BAD_COMMAND("usage: %s <client-id>/<window-id> width height", argv[0]);
+
+      TestClient *client;
+      const char *window_id;
+      if (!test_case_parse_window_id (test, argv[1], &client, &window_id, error))
+        return FALSE;
+
+      if (!test_client_do (client, error, argv[0], window_id,
+                           argv[2], argv[3], NULL))
+        return FALSE;
+    }
   else if (strcmp (argv[0], "hide") == 0 ||
            strcmp (argv[0], "activate") == 0 ||
            strcmp (argv[0], "raise") == 0 ||