Implement copysign, sign, and signbit ufuncs

[juntyr]

Supersedes #118

Progress on #111

• implements the sign, signbit, and copysign ufuncs
• extends unary unfunc tests
• adds extra const annotations to the ops implementations

[juntyr]

@SwayamInSync A manual rebase was easier for me, this PR should now be good to go

[juntyr]

@SwayamInSync @ngoldbaum Is there anything left to do so that this PR can be merged?

[SwayamInSync]

@SwayamInSync @ngoldbaum Is there anything left to do so that this PR can be merged?

Yes just a small edit, in the earlier review I mentioned a variable shadowing issue, can you please fix that, it is not causing any error right now because inside loop statements the lists gets interpreted first. So it captures the original value. But this is confusing and error-prone.

[juntyr]

@SwayamInSync @ngoldbaum Is there anything left to do so that this PR can be merged?

Yes just a small edit, in the earlier review I mentioned a variable shadowing issue, can you please fix that, it is not causing any error right now because inside loop statements the lists gets interpreted first. So it captures the original value. But this is confusing and error-prone.

I'm unfortunately unable to find that review, could you please link it for me?

[SwayamInSync]

Thanks LGTM

[ngoldbaum]

I'm glad you two are handling reviews between each other. Please feel free to ping me if you'd like an additional eye or opinion on anything.