The square root operator implementation for fixed-point numbers

[blewater]

• Added the core sqrt function to Fixed, calculating the scaled square root and remainder.
• Uses i128 for intermediate calculations (t = input.0 * SCALE_FACTOR) to avoid overflow.
• Includes int_sqrt helper using Newton's method for u64.
• Lots of unit tests for operator and constraint evaluation.

eval_fixed_sqrt Constraint (eval.rs):
Enforces the constraint out^2 + rem = input * SCALE_FACTOR

[raphaelDkhn]

Very nice implementation @blewater, thanks! I just added some optimizations to avoid using i128. And I added a constraint to make sure the input is non-negative.

[raphaelDkhn]

@all-contributors add @blewater for code

[allcontributors]

@raphaelDkhn

I've put up a pull request to add @blewater! 🎉