Fix traverse for Either and Option

[serras]

@nomisRev realized that our current implementations of traverse do not respect the expected laws. Let's compare with Haskell (where Just is the equivalent of Some, and [x] means listOf(x)).

> mapM (\x -> Just 3) (Left 2)
Just (Left 2)
> mapM (\x -> [3]) (Left 2)
[Left 2]

However, our current implementation would return None and an empty list in those cases. This PR implements the law-abiding implementations, which return Left wrapped in the corresponding type instead of the "error path" of those.

One important question here is whether we should consider this a bug, and thus just release the modifier implementation as part of 1.2.0, or whether this is a breaking change, and thus we should wait until 2.0 and release this fixed implementation under a different name.

Note: the implementation for Ior seems to be lawful.

[github-actions]

Kover Report

File	Coverage [55.24%]
arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Either.kt	57.00%
arrow-libs/core/arrow-core/src/commonMain/kotlin/arrow/core/Option.kt	53.02%

Total Project Coverage	44.30%

[franciscodr]

There are a few missing imports in the ReplaceWith expressions

[gutiory]

Apart from @franciscodr suggestions, LGTM!

[franciscodr]

Thanks, @serras!