New mutation operator: ABS(Absolute Value Mutator)

[ligurio]

The worst performing mutator was ABS(Absolute Value Mutator) that would replace an expression with ±abs(expression), for example: absl::Minutes(10) - elapsed; --> absl::Minutes(-abs(10)) - elapsed;

Googler described an interesting mutation operator in his article about mutation testing in Google.
https://testing.googleblog.com/2021/04/mutation-testing.html

[AlexDenisov]

Just for reference, we have cxx_minus_to_noop that removes unary minus.
I see a value in the ABS operator, but I cannot give any ETA when (and if) it will be implemented.