RFID sensor and tag

[chapulina]

Gazebo-classic had partial support for RFIDSensors that could detect RFIDTags. Unfortunately, I haven't found any working examples of that sensor, so I'm not sure whether that implementation works.

But in any case, this sensor would be a nice addition to Ignition since it's common that users need it. I remember needing something like this for ServiceSim and we ended up implementing a custom plugin to do that.