[Feature] Integer square root

[d0cd]

This PR introduces:

• console and circuit implementations of integer square root.

Resource: https://en.wikipedia.org/wiki/Integer_square_root

TODO:

• [ ] Integrate into opcodes
• [ ] Guard by consensus version
• [ ] Soundness analysis
• [ ] Optimizations
  • (x + 1)^2 > y ==> x^2 + 2x + 1 > y ==> 2x + 1 > y - x^2 (checked subtraction)
  • x^2 <= y ==> 0 <= y - x^2