Float Multiarray Publisher

## Issue template

- Hardware description: ESP32
- Installation type: micro_ros_arduino library in legacy Arduino IDE with docker container for agent. USB serial transport
- Version or commit hash: humble

#### Expected behavior

Micro ros publishes an array of 32bit floats

#### Actual behavior

ESP32 boot loops, publishes nothing, or code doesn't compile

#### Additional information

Hi All,

I've spent the last few days trying to get micro ros to publish a float array. I'm simply looking for some example code that shows me how to publish to a topic with a Float32MultiArray Message and how to publish data to the different array elements.

I'm pretty sure my issue lies in the memory allocation area. I don't have any useful code to share as it's a conglomeration of broken things I've found all over the internet.

I really just need help with a quick example script to publish a Float32MultiArray.

Thank you

No files, tests, or entry points are named. Start by reproducing the ESP32 setup with the micro_ros_arduino library, legacy Arduino IDE, Docker agent, and USB serial transport, then review how Float32MultiArray memory and elements are handled. Done means a concise example compiles and publishes a float array without boot loops.

Written by the indexing model from the issue text.