[link-metrics] implement link metrics manager (#9375)

This commit implements a new module LinkMetricsManager, which utilizes
the Link Metrics feature to get the Link Metrics data from neighboring
devices.

The commit also adds a few tests to the module:
- Unit Test: tests/unit/test_link_metrics_manager.cpp, will be run in
  `unit-tests` in `unit.yml`.
- Expect Test: tests/scripts/expect/v1_2-linkmetricsmgr.exp, will be
  run in `expects` in `simulation-1.2.yml`.
- Simulation Test:
  tests/scripts/thread-cert/v1_2_LowPower_test_link_metrics_manager.py,
  will be run in `packet-verification-low-power` in
  `simulation-1.2.yml`.

tests/scripts/expect/v1_2-linkmetricsmgr.exp

@@ -0,0 +1,60 @@
+#!/usr/bin/expect -f
+#
+#  Copyright (c) 2023, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+source "tests/scripts/expect/_common.exp"
+source "tests/scripts/expect/_multinode.exp"
+
+setup_two_nodes
+
+switch_node 1
+send "linkmetricsmgr enable\n"
+expect_line "Done"
+
+sleep 10
+
+switch_node 2
+set addr [get_ipaddr mleid]
+
+switch_node 1
+send "ping $addr\n"
+expect "16 bytes from $addr: icmp_seq=1"
+send "linkmetricsmgr show\n"
+expect -re {ExtAddr:([0-9a-f]){16}, LinkMargin:\d+, Rssi:\-?\d+}
+expect "Done"
+
+sleep 5
+
+send "linkmetricsmgr disable\n"
+expect_line "Done"
+send "linkmetricsmgr show\n"
+expect_line "Done"
+send "linkmetricsmgr xxx\n"
+expect_line "InvalidCommand"
+
+dispose_all