sensor-cache: Implement reading data

Implement reading data in property changed callback.
With sensor-cache, the sensor's property is returned by the
callback of propertiesChanged match, parse the property from the message
and generate the sensor's response.

Tested: Verify the sensors using `readingData` have valid values in
        QEMU, e.g.

        Inlet_Temp       | 20.000     | degrees C  | ok    | na        | 0.000     | 5.000     | 38.000    | 43.000    | na

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: I2c6328cb6001d0daf2045d17e73773dccf55d521
3 files changed