Array<T: ContentEquatable> does not conform to ContentEquatable

[nkristek]

Checklist

• Reviewed the README and documents.
• Searched existing issues for ensure not duplicated.

Description

Similar to the conditional Equatable conformance Array<T: ContentEquatable> should also conditionally conform to ContentEquatable.

Motivation and Context

This potentially simplifies the implementation of ContentEquatable and thus Differentiable of a container type, if it contains an array of equatable/differentiable items.

Proposed Solution

extension Array: ContentEquatable where Element: ContentEquatable {
    @inlinable
    public func isContentEqual(to source: Array<Element>) -> Bool {
        return count == source.count
            && zip(self, source).allSatisfy { $0.isContentEqual(to: $1) }
    }
}