tests: fs: ext2: Add basic fs test

Use test_fs_basic test in ext2 tests.

Signed-off-by: Franciszek Zdobylak <fzdobylak@antmicro.com>

tests/subsys/fs/ext2/src/test_basic.c

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2023 Antmicro
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/ztest.h>
+#include <zephyr/fs/fs.h>
+
+#include "utils.h"
+
+void test_fs_basic(void);
+
+/* Expected by test_fs_basic() */
+struct fs_mount_t *fs_basic_test_mp = &testfs_mnt;
+
+ZTEST(ext2tests, basic)
+{
+	/* Common basic tests.
+	 * (File system is mounted and unmounted during that test.)
+	 */
+	test_fs_basic();
+}