compile for android when doing a mujoco release

[joanllobera]

The compilation of mujoco for android could easily be included in each new release, and it would be easier to use it.

I give more context for our particular use case:

We are using mujoco in Unity, and using it in VR experiences. The fact that each release is compiled for linux, apple and windows is fantastic, since we use the three of them. To avoid mixups in Unity, I have set up a simple package called mujoco-bin that sistematizes the import of the packages. It allows compiling any project using mujoco for all the platforms, without having to set up how each version of the mujoco library is imported.

However, these days most VR headsets are based on android. So, to update mujoco-bin we need to recompile each mujoco release for android, and add it to the package. The result is this:
https://github.com/joanllobera/mujoco-bin/tree/main/Runtime/Plugins/Android

This works fine, but the compilation for android could easily be integrated in the release pipeline that compiles for every other platform.
Here there is a description on how we do it: https://github.com/yvesantzero/mujoco/blob/main/build_mujoco_android.pdf

It would be great if what is described in the pdf could be integrated in the pipeline that generates the releases.