cmd: xxd: add new command

Add xxd command to print file content as hexdump to standard out

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Roger Knecht <rknecht@pm.me>

test/py/tests/test_xxd/test_xxd.py

@@ -0,0 +1,23 @@
+# SPDX-License-Identifier:      GPL-2.0+
+
+""" Unit test for xxd command
+"""
+
+import pytest
+
+@pytest.mark.boardspec('sandbox')
+@pytest.mark.buildconfigspec('cmd_xxd')
+def test_xxd(u_boot_console, xxd_data):
+    """ Unit test for xxd
+
+    Args:
+        u_boot_console -- U-Boot console
+        xxd_data -- Path to the disk image used for testing.
+    """
+    response = u_boot_console.run_command_list([
+        f'host bind 0 {xxd_data}',
+        'xxd host 0 hello'])
+
+    assert '00000000: 68 65 6c 6c 6f 20 77 6f 72 6c 64 0a 00 01 02 03  hello world.....\r\r\n' + \
+           '00000010: 04 05                                            ..' \
+           in response