Decompose `IdentifiableComponent` to `Identifiable` and `Component`

[Ryo Aoyama]

Checklist

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

Description

Decompose IdentifiableComponent to Identifiable and Component.

Motivation and Context

Use protocol composition like SwiftUI.

Proposed Solution

Use Swift.Identifiable if Swift version is greater than 5, and creates Carbon.Identifiable protocol if not.
e.g.

#if swift(<5)

public protocol Identifiable {
    associatedtype ID: Hashable

    var id: ID { get }
}

#endif

typealias IdentifiableComponent = Identifiable & Component

IdentifiableComponent will be deprecated in the future, but not now.

[Ryo Aoyama]

Swift.Identifiable depends on iOS 13 due to ABI stability. This means that can't decides whether to use Identifiable typealias at compile time.
Close this issue to avoid ambiguous type declaration in Swift.Identifiable and Carbon.Identifiable.