Generic Qt Sensors Backend (plugin) implementation

The purpose of this story is to propose the way of generic plugin implementation. If we can provide a generic way which is easily configurable (from JSON or similar) and abstracting the methods of data retrieval, we might be able to support more sensors with less maintenance of effort.

My assumption is that most of the sensors are connected via wired (I2C/SPI/UART,...) and wireless (BLE, Zigbee, LoRa,...) interfaces, but the code converting the raw data should be similar.

To achieve this goal, we need to keep the implementation of sensor-specific plugins as general as possible. Ideally, the plugin is only used to process the incoming raw data, and then forward to QtSensors front-end. It doesn't matter where the raw data comes from.

Meanwhile, we need to consider how to easily add different connectivity (wired, wireless) to it later on. If we can move the connectivity related code to a shared interface, the user can configure the interface connecting to the sensor themselves.