Micro-ROS communication

Communication from ROS-network to MCU, thrugh a serial DDS xrce agent running on the RPI.

Compile and Run microros ping-pong example between:

• VM and STM32F446RE
• RPI and STM32F446RE

Exchange custom ROS messages between:

• VM and STM32F446RE
• RPI and STM32F446RE

Add documentation to the repository for future reference:

• Update repository with config for microros inclusion in crosscompilation for STM32F446RE