refactor: extract duplicated velocity calculation logic in Contact class

[diogomene]

What was done?

To eliminate the code duplication identified in the Contact class during the calculation of the relative velocity between two contact points (bodies A and B), the repeated instructions were extracted and centralized into a method named computeRelativeVelocity within the Contact class:

computeRelativeVelocity(
  dv: Vec2Value,
  vA: Vec2Value,
  wA: number,
  rA: Vec2Value,
  vB: Vec2Value,
  wB: number,
  rB: Vec2Value
): void {
  matrix.zeroVec2(dv);
  matrix.plusVec2(dv, vB);
  matrix.plusVec2(dv, matrix.crossNumVec2(temp, wB, rB));
  matrix.minusVec2(dv, vA);
  matrix.minusVec2(dv, matrix.crossNumVec2(temp, wA, rA));
}

This function takes the required parameters and performs the necessary calculations in-place by reference.

With this solution, the duplication has been effectively addressed, improving both the readability and understanding of the code through modularization and reuse of instructions. Additionally, any future changes to the calculation logic can now be made in a single function, avoiding the need to update all three occurrences of the routine.

Resolves #305

[shakiba]

@diogomene thanks reviewing the code and finding potential improvements. The code is intentionally verbos to make it easier to read, debug, and profile for performance optimization. It's also easier for browser to optimize at runtime.

As you mentioned, verbos and repetitive code is more difficult when you update the logic, however we almost don't change the logic.

[diogomene]

@shakiba. Understood. As long as the code is not overly repetitive and not used in other classes, keeping its locality while calling the procedure within the class may be better.

If the logic is unlikely to change, I see no risks in repeating the code within the class.

Thank you so much for the review; I truly appreciate your time and attention.