Align 2.3

This release focuses on filling the remaining gaps in the API.

• Constraints type now conforms to Collection protocol (backed by Array)
• Add Constraints activate() and deactivate() methods
• Add clamp(to limit: ClosedRange<CGFloat>) API for dimension anchors
• Add default insets argument for AnchorCollectionEdges equal method
• Replace the target parameter of AnchorCollectionEdges equal method with LayoutItem
• Add AnchorCollectionEdges variant that works with CGFloat
• Add AnchorCollectionEdges lessThatOrEqual() method
• Fix AnchorCollectionCenter lessThatOrEqual() method
• Replace the target parameter of AnchorCollectionCenter method with LayoutItem
• Performance optimizations