Add support for Video4Linux devices and include it in the autotest
This MR brings support for Video4Linux devices (webcams). This is a prerequisite to add system settings for Video4Linux that I'm working on and apply the settings on plug in.
The modifications are "heavily" taken from the Camera device support.
Here are outputs from my testing from this branch: solid-hardware5-details-output.txt
solid-hardware5-list-output.txt