generalizes `deleteBy` parameter type

[acple]

This generalizes deleteBy parameter without any implementation changes.

Current problem is that we must have actual value or a dummy of the type of array item while using deleteBy:

type Id = Int
type ComplicatedRecord = { id :: Id, a :: String, b :: Boolean, c :: ... }

deleteById :: Id -> Array ComplicatedRecord -> Array ComplicatedRecord
deleteById id = ? -- cannot implement with `deleteBy` unless creating dummy value of ComplicatedRecord

This PR allows it like this:

deleteById :: Id -> Array ComplicatedRecord -> Array ComplicatedRecord
deleteById = deleteBy \id item -> id == item.id

I believe this PR is almost non-breaking, however, there is a slight possibility of breakage related to type inference things. I verified that the all of latest package-set items can be built with this change.

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Alternative approach:

delete :: forall a. Eq a => a -> Array a -> Array a
delete x = deleteBy (eq x)

deleteBy :: forall a. (a -> Boolean) -> Array a -> Array a
deleteBy p xs = _

-- usage
deleteById :: Id -> Array _ -> Array _
deleteById id = deleteBy \item -> id == item.id

This has more clear signature similar to filter and easy to understand but is a Breaking-change.

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Checklist:

• [x] Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
• [ ] Linked any existing issues or proposals that this pull request should close
• [ ] Updated or added relevant documentation
• [ ] Added a test for the contribution (if applicable)

[acple]

I decided put this change as Other improvements rather than Breaking changes or New features. I'm not sure which category was most appropriate for this.