[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`.

script/test

@@ -129,6 +129,7 @@ build_simulation()
         options+=("-DOT_CSL_RECEIVER=ON")
         options+=("-DOT_LINK_METRICS_INITIATOR=ON")
         options+=("-DOT_LINK_METRICS_SUBJECT=ON")
+        options+=("-DOT_LINK_METRICS_MANAGER=ON")
     fi
 
     if [[ ${ot_extra_options[*]+x} ]]; then
@@ -162,6 +163,9 @@ build_posix()
     if [[ ${version} != "1.1" ]]; then
         options+=("-DOT_DUA=ON")
         options+=("-DOT_MLR=ON")
+        options+=("-DOT_LINK_METRICS_INITIATOR=ON")
+        options+=("-DOT_LINK_METRICS_SUBJECT=ON")
+        options+=("-DOT_LINK_METRICS_MANAGER=ON")
     fi
 
     if [[ ${FULL_LOGS} == 1 ]]; then