Release arduino-91.8

Yocto
- [INITRAMFS] Fixed linuxrc script for initramfs images
- [DRIVER] Added out of tree lan865x module
- [TRACEABILITY] Append arduino layer sha in /etc/os-release
- [OFFLINE UPDATE] Use RGB led to signal success / failure, more robust handling
- [OOTB] Refactor usb gadget creation script and handle usb gadget removal

Based on LmP v91 https://foundries.io/products/releases/91/

NOTE: this is the Yocto manifest. For docker compose apps, checkout

https://github.com/arduino/portenta-containers/tree/release

Author: MaxPayne86