Implement Missing Greybus Protocols in Zephyr

BeagleBoard devices currently lack support for Greybus Camera and Audio class protocols, preventing them from acting as multimedia bridges. This project implements these missing protocols within the Zephyr RTOS subsystem by mapping Greybus operations to Zephyr's native video and audio driver APIs. To guarantee reliability over constrained network transports, the architecture leverages hardware-level compression and strict buffer management. Deliverables include fully validated native_sim mock endpoints with comprehensive ztest suites, physical hardware transport validation on the BeagleConnect Freedom and BeaglePlay using optimized peripherals, and a robust set of upstream pull requests.