Combined, both options greatly improve camera depth accuracy compared to
OpenGL default Z mapping and int24 depth buffer.
Requires GL_ARB_clip_control and ARB_depth_buffer_float extensions
This PR added necessary annotations, following what we did for mjData
and mjModel for length of the given array.
This is useful because my parser used to generate Swift interface:
https://github.com/liuliu/swift-mujoco/blob/main/Sources/codegen/main.swift#L297
such that the access to underlying array is bound-checked.
Please let me know if this makes sense. After this change, I can
successfully generate all mj* struct interfaces in Swift without problem
(with notable exception of mjui): https://github.com/liuliu/swift-mujoco/tree/main/Sources