enable health_monitor new implementation

Add health_monitor interface and implementation. Enable the
health_monitor from existing healthMonitor flow.
This change is in relation to following design and D-Bus interface
update -
https://gerrit.openbmc.org/c/openbmc/docs/+/64917
https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/64914

Tested:
```
busctl tree xyz.openbmc_project.HealthMon
`- /xyz
  `- /xyz/openbmc_project
    `- /xyz/openbmc_project/metric
      `- /xyz/openbmc_project/metric/bmc
        |- /xyz/openbmc_project/metric/bmc/cpu
        | |- /xyz/openbmc_project/metric/bmc/cpu/kernel
        | |- /xyz/openbmc_project/metric/bmc/cpu/total
        | `- /xyz/openbmc_project/metric/bmc/cpu/user
        |- /xyz/openbmc_project/metric/bmc/memory
        | |- /xyz/openbmc_project/metric/bmc/memory/available
        | |- /xyz/openbmc_project/metric/bmc/memory/buffered_and_cached
        | |- /xyz/openbmc_project/metric/bmc/memory/free
        | |- /xyz/openbmc_project/metric/bmc/memory/shared
        | `- /xyz/openbmc_project/metric/bmc/memory/total
        `- /xyz/openbmc_project/metric/bmc/storage
          |- /xyz/openbmc_project/metric/bmc/storage/rw
          `- /xyz/openbmc_project/metric/bmc/storage/tmp

curl -k https://localhost:8443/redfish/v1/Managers/bmc/ManagerDiagnosticData
--user "root:0penBmc"
{
  "@odata.id": "/redfish/v1/Managers/bmc/ManagerDiagnosticData",
  "@odata.type": "#ManagerDiagnosticData.v1_2_0.ManagerDiagnosticData",
  "FreeStorageSpaceKiB": 3,
  "Id": "ManagerDiagnosticData",
  "MemoryStatistics": {
    "AvailableBytes": 354029533,
    "BuffersAndCacheBytes": 79077333,
    "FreeBytes": 291730033,
    "SharedBytes": 11876000,
    "TotalBytes": 425516000
  },
  "Name": "Manager Diagnostic Data",
  "ProcessorStatistics": {
    "KernelPercent": 16.1534,
    "UserPercent": 10.6638
  },
  "ServiceRootUptimeSeconds": 834.753
}

```

Change-Id: I1e9fac226b438f0556cb20321f1f2b6d51af7dbc
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/health_utils.hpp b/health_utils.hpp
index b89d8e5..ded0159 100644
--- a/health_utils.hpp
+++ b/health_utils.hpp
@@ -12,5 +12,7 @@
 
 /** @brief Start a systemd unit */
 void startUnit(sdbusplus::bus_t& bus, const std::string& sysdUnit);
+/** @brief Find D-Bus paths for given interface */
+auto findPaths(sdbusplus::bus_t& bus, const std::string& iface) -> paths_t;
 
 } // namespace phosphor::health::utils