bullet-featherstone: Add support for category bitmask

[iche033]

🎉 New feature

builds on top of #804

Summary

Adds support for category bitmask for the bullet-featherstone physics engine. This PR implements the strategy outlined gazebosim/sdformat#1630 that adds this new feature while preserving existing behavior when only collide bitmasks are set.

Note: another important change I made in this PR is that I had to manually call world->getCollisionWorld()->performDiscreteCollisionDetection(); again (after clearing the broadphase cache and stepping sim) to force generation of up-to-date contact points in the same iteration. Without this, incorrect contacts are generated and the test fails.

Test it

New test added in simulation_features.cc

To run

cd build/gz-physics
ctest -R simulation_features_bullet-featherstone

You can also play with the test world:

gz sim -v 4 -r <path_to>/gz-physics/test/common_test/worlds/shapes_category_bitmask.sdf --physics-engine libgz-physics-bullet-featherstone-plugin

Boxes are grouped by colors, i.e. have the same category bitmasks, so boxes of the same color should not collide with each other.

Checklist

• Signed all commits for DCO
• Added a screen capture or video to the PR description that demonstrates the feature
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• Updated Bazel files (if adding new files). Created an issue otherwise.
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