Add native MyoSuite EnvPool integration

[Trinkle23897]

Summary

• adds native C++ EnvPool coverage for the pinned MyoSuite v2.11.6 surface using generated upstream metadata and third_party/myosuite assets
• wires MyoBase, MyoChallenge, and MyoDM TrackEnv registration, docs, oracle utilities, render comparison, and release packaging
• carries forward the previous MyoSuite integration branch and fixes Windows render/oracle initialization so Mesa DLLs load before MuJoCo/native imports

Local validation

• make ruff
• make mypy
• make cpplint
• bazel test --test_output=errors //envpool/mujoco:myosuite_metadata_test //envpool/mujoco:myosuite_asset_smoke_test //envpool/mujoco:myosuite_myobase_test //envpool/mujoco:myosuite_myodm_test //envpool/mujoco:myosuite_myochallenge_test
• bazel test --test_output=errors //envpool/mujoco:myosuite_render_doc_test
• bazel test --test_output=errors --test_sharding_strategy=disabled --test_arg=--myosuite_render_shard_index=0 --test_arg=--myosuite_render_shard_count=50 //envpool/mujoco:myosuite_render_surface_test
• bazel test --test_output=errors --test_sharding_strategy=disabled --test_arg=--myosuite_render_shard_index=25 --test_arg=--myosuite_render_shard_count=50 //envpool/mujoco:myosuite_render_surface_test
• bazel test --test_output=errors --test_sharding_strategy=disabled --test_arg=--myosuite_render_shard_index=49 --test_arg=--myosuite_render_shard_count=50 //envpool/mujoco:myosuite_render_surface_test

Draft status

This is draft until the remaining oracle-alignment bar is resolved: current tests still include scoped alignment tolerances and MyoBase/MyoDM representative step-level oracle coverage instead of full bitwise coverage over every direct ID.