fix the device owner ship model

[firesurfer]

What changes

This PR changes the device owner ship model to a more sane approach. In the same step the GenericEthercatDevice and the EthercatDeviceBase were fused into a single EthercatDevice class.

Example how this affects the downstream users

1. Old setup -> device is attached to the bus

EthercatBus bus;

MyFancyDevice device;
bus.attach_device(device_id, device.get_ethercat_device());

2. New setup -> device is handed out by the bus

EthercatBus bus;
MyFancyDevice device(bus->aquired_device(device_id));

Why

1. More sane approach -> the generic adapter is handled fully by the bus
2. This approach allows a better synchronization model in the future (aka sync all devices at once into the bus with less synchronization overhead)

[bpapaspyros]

overall looking good, just trying to wrap my head around the threading parts.

Also, does keeping all devices in one vector and then mutex locking creating a bottleneck in some places? perhaps it's insignificant even. (I'm re-reading, but I wanted to already post the syntactic/code comments that came to mind)

[bpapaspyros]

looks good then, thanks for the explanations