Enable default color stream if none is enabled in RealSense2FrameGrabber

[cansik]

As mentioned in bytedeco/procamcalib#26 this is a small fix for the RealSense2FrameGrabber to automatically enable the default color stream (in RGB8 format). The same behaviour is also implemented in the RealSenseFrameGrabber.

[cansik]

Added support for stream selection and default stream activation as discussed in bytedeco/procamcalib#25.
Switched to default width, height, framerate properties (bytedeco/procamcalib#26).

By default a color, depth and ir stream is enabled and can be selected by the videoStream attribute (in the same order).

[saudet]

Looks good! Is there a way to detect when there are more than a single IR sensor and enable the second one too by default? @Faaux was asking about support for that.

[cansik]

Yes, we could check if a stream exists, but if so, I would do it as well for the depth and first IR stream. There are tracking cameras models which only have two color sensors for feature detection and no depth image.

I guess it makes sense to list all the sensors and their video-streams and enable all of them. This approach allows us to support all camera models (current & future).

[cansik]

Implementation to enable all video streams matching the requested width, height and frameRate is done. I am sorting the streams now by the stream_type id, which means the order at the moment is depth < color < ir.

[saudet]

Sounds good enough. Should we merge? You've tested this and everything works as intended?

[cansik]

I could not test it with all the devices, but with the D455 and D435 it worked as expected. I would say we are ready to merge 🚀