utest: move cpp from examples to components/libc/cplusplus

Also update the case names to compatible with naming rules.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>

components/libc/cplusplus/utest/tc_lambda.cpp

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2006-2025, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2025-09-19     Rbb666       the first version
+ */
+
+#include <rtthread.h>
+#include "utest.h"
+
+/**
+ * @brief Test basic lambda expression.
+ */
+static void test_lambda_basic(void)
+{
+    auto lambda = []() { return 42; };
+    if (lambda() != 42)
+    {
+        uassert_false(true);
+    }
+    uassert_true(true);
+}
+
+/**
+ * @brief Test lambda with capture.
+ */
+static void test_lambda_capture(void)
+{
+    int x = 10;
+    auto lambda = [x]() { return x * 2; };
+    if (lambda() != 20)
+    {
+        uassert_false(true);
+    }
+    uassert_true(true);
+}
+
+static rt_err_t utest_tc_init(void)
+{
+    return RT_EOK;
+}
+
+static rt_err_t utest_tc_cleanup(void)
+{
+    return RT_EOK;
+}
+
+static void testcase(void)
+{
+    /* Test basic lambda expression */
+    UTEST_UNIT_RUN(test_lambda_basic);
+    /* Test lambda with capture */
+    UTEST_UNIT_RUN(test_lambda_capture);
+}
+UTEST_TC_EXPORT(testcase, "components.libc.cpp.lambda_tc", utest_tc_init, utest_tc_cleanup, 10);