Exclude overlapping collidable points during collision parsing

[flferretti]

This PR implements a logic to filter out overlapping collidable points when extracting their positions, ensuring unique points are processed for contact parameters. This is particularly useful when dealing with closed-loop kinematic chains or ErgoCub models

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📚 Documentation preview 📚: https://jaxsim--382.org.readthedocs.build//382/

[younik]

LGTM!
Do we want it JAXSIM_COLLISION_INCLUDE_OVERLAPS=False by default?
(Just asking because previously it was working as if it was True)

[flferretti]

LGTM! Do we want it JAXSIM_COLLISION_INCLUDE_OVERLAPS=False by default? (Just asking because previously it was working as if it was True)

Thanks @younik! I'm getting some errors in CI which I need to fix, but once fixed, we may consider leaving this on by default as it can improve performances on some models