Added world linear and angular velocity reset components for link to `set_model_state` plugin

[yaswanth1701]

🎉 New feature

Follow up PR to #2359

Summary

This PR introduces WorldLinearVelocityReset and WorldAngularVelocityReset components for the LInk entity to set initial link velocities from SDF using set_model_state plugin. The link velocities are only set to root link of the FreeGroup for now.

Test it

gz sim -v 4 examples/worlds/set_model_state.sdf

Should see the red cube moving and rotating.

Checklist

• [X] Signed all commits for DCO
• [X] 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)
• [ ] While waiting for a review on your PR, please help review another open pull request to support the maintainers

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