Switch to use standard rosdoc2 instead of custom ament_cmake_doxygen

[tfoote]

We'd rather not rely on the non-upstream tool. It was a workaround for building docs locally for now.

We'll need to replace this before we have successful public builds of docs on the ros2 buildfarm.

[francocipollone]

Can I move this issue directly to maliput_infrastructure(or even maliput_documentation) as this affects all the repositories?

[tfoote]

Sure, I just filed it here as this package needed a fix.

[francocipollone]

We are currently relying on ament_cmake_doxygen for documentation creation.
One convenient feature of this tool is that, when building documentation for a package, one can indicate to consume the generated documentation for the upstream's packages in a way that the linking between documentations of different repositories can be handled.

Example: when building documentation up-to maliput_malidrive, if I go to maliput_maldrive docs, I will find valid links to maliput package docs.
maliput_documentation takes advantage of this, being the package that gathers the documentation of all the repos.

rosdocs2 seems to be great for generating documentation for single packages, and certainly using this standard tool will be great, however my only concern is about linking properly linking to upstream docs for easier doc exploration.