[NFC] Update doxygen build and configuration files

[jasnell]

I know that doxygen isn't everyone's favorite thing, but I've found it useful, but it hasn't been updated in a bit. This PR updates it and adds a just ds (doxygen-serve) command to easily serve the generated docs for local browsing.

The doxygen build is added because doxygen needs to be built with the correct clang version to avoid warnings and errors.

I had claude do the bazel bits because I really hate dealing with build systems.