[WIP] Arithmetic circuit library subtractors

[ManjulaGandhi]

Summary

Implementing Twos Complement Subtractor

Details and comments

Tests are still missing

[jakelishman]

@Cryoris: I don't know the purpose of the classical arithmetic parts of the circuit library, but I think you might know the history. This PR is old and never saw review, but is from around the time of some other modifications to the arithmetic library (esp #6470) - please could you judge if it's something useful that we should include, or close the PR if not?

[Cryoris]

Yeah this would be useful to have to complete the operations in the arithmetic circuit library 🙂

@ManjulaGandhi would you still be interested in pursuing this? Otherwise we can also close it and see if we can pick it up in the future 🙂

[ManjulaGandhi]

@Cryoris yes interested to complete this task.

[jakelishman]

I'm going to close this PR now due to lack of activity, but if @Cryoris and @ManjulaGandhi are committed to getting this actually merged, please feel free to re-open it.