Introduce ignoreFailIfHostOff config setting

Some sensors only provide valid readings when the host is powered on.
This change introduces the `ignoreFailIfHostOff` configuration option to
differentiate between unavailable readings based on host state.

- Host OFF: Sensor unavailable is acceptable and will not be treated as
a failure.
- Host ON (running): Sensor unavailable is unexpected, and the failsafe
mode will be triggered.

This ensures that sensors dependent on host power state are handled
correctly without causing unnecessary failsafe triggers during host-off.

Tested on Catalina: failsafe mode is not triggered when the host is off.
- config.json example: add `ignoreFailIfHostOff` for sensors only
available when the host is on.
```
{
    "sensors": [
        ......
        {
            "name": "HDDBOARD_SSD0_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/HDDBOARD_SSD0_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "HDDBOARD_SSD2_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/HDDBOARD_SSD2_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "PDB_P48V_HSC1_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/PDB_P48V_HSC1_TEMP_C",
            "timeout": 0,
            "ignoreDbusMinMax": true
        },
        {
            "name": "PDB_VR_P12V_N1_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/PDB_VR_P12V_N1_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "PDB_VR_P12V_N2_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/PDB_VR_P12V_N2_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "IOB0_NIC0_OSFP_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/IOB0_NIC0_OSFP_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "IOB0_NIC1_OSFP_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/IOB0_NIC1_OSFP_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "IOB1_NIC0_OSFP_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/IOB1_NIC0_OSFP_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        {
            "name": "IOB1_NIC1_OSFP_TEMP_C",
            "type": "temp",
            "readPath": "/xyz/openbmc_project/sensors/temperature/IOB1_NIC1_OSFP_TEMP_C",
            "timeout": 0,
            "ignoreFailIfHostOff": true,
            "ignoreDbusMinMax": true
        },
        ......
    ],

    "zones": [
        ......
    ]
}
```

Change-Id: I5355c453ca3c6d918c197dcd2cc9119e471d615d
Signed-off-by: Potin Lai <potin.lai@quantatw.com>
diff --git a/sensors/pluggable.cpp b/sensors/pluggable.cpp
index f9844f5..491152f 100644
--- a/sensors/pluggable.cpp
+++ b/sensors/pluggable.cpp
@@ -16,6 +16,7 @@
 
 #include "pluggable.hpp"
 
+#include "hoststatemonitor.hpp"
 #include "interfaces.hpp"
 
 #include <cstdint>
@@ -41,7 +42,18 @@
 
 bool PluggableSensor::getFailed(void)
 {
-    return _reader->getFailed();
+    bool isFailed = _reader->getFailed();
+
+    if (isFailed && getIgnoreFailIfHostOff())
+    {
+        auto& hostState = HostStateMonitor::getInstance();
+        if (!hostState.isPowerOn())
+        {
+            return false;
+        }
+    }
+
+    return isFailed;
 }
 
 std::string PluggableSensor::getFailReason(void)