Add traverse, zip and orEmpty to Option

[millyrowboat]

This PR adds three new extension methods to Option:

• traverseOp
  • traverse is currently shadowed in Arrow, so I had to rename it
  • It is a function that allows you to iterate over an Monad Option with in the context of an Either, and turn your Option<A> into an Either<None, Option<B>>
• zipOp
  • We were umming and ahhing about whether to include this in Quiver. I'm not attached to it since you can achieve similar results with just map
  • This is a function that will combine your Option<A> with a Option<B> and return an Option<C>
• orEmpty is a convenience function that we've been using in our codebases, that will return an empty string if your Option is None
  • Wondering now if that should only be allowed to be called on a Option<String> context. Thoughts?

[Synesso]

Suggested change

	}
	}

[aparkersquare]

I think the indent on line 46 is actually correct (2).

But the following two tests have incorrect indent (4).

[aparkersquare]

It's unfortunate we have to use traverseOp and zipOp, that really reduces the value of back-porting these.

[aparkersquare]

traverseEither and zipOption would be more consistent with the variants on NonEmptyList (which have recently been back-ported to quiver).

We could then add traverse and zip when arrow finally removes them?

[cwmyers]

I feel like using straight traverse and zip is worth the wait. Let's lean on Arrow to fully remove them.

[millyrowboat]

Agreed. I'll open a new PR with just orEmpty then if you're happy with it