Improve Doxygen integration with kbuild-based firmware

[gemenerik]

With #1485, we're adding a workaround that allows the documentation to build by temporarily disabling Doxygen's "warnings as errors" setting. This unblocks the web build, but the documentation is still incomplete and not rendering as desired.

The underlying problem is that autoconf.h, which contains the kbuild-generated configuration, is not generated unless the firmware is built, and our documentation builder Docker image currently lacks arm-none-eabi-gcc, so we can't perform that build step.

Potential solutions:

• Include arm-none-eabi-gcc in the doc builder docker so that the necessary configuration files can be generated as part of the build process.
• Explore parsing the Kconfig files directly (or using an intermediate output format from kbuild) to avoid relying on C headers like autoconf.h.

This issue tracks the goal of making Doxygen integration more robust with the Crazyflie firmware's kbuild system and removing the need for workarounds like disabling warnings.