FIX: layer layout animation at start (Juanpe#549)

Author: nazadigio

SkeletonViewCore/Sources/Internal/UIKitExtensions/UIView+SkeletonView.swift

@@ -105,7 +105,8 @@ private extension UIView {
         }) { subview in
             subview.recursiveShowSkeleton(skeletonConfig: config)
         }
-
+        layoutSkeletonIfNeeded()
+        
         if let root = root {
             _flowDelegate?.didShowSkeletons(rootView: root)
         }
@@ -126,7 +127,8 @@ private extension UIView {
         }) { subview in
             subview.recursiveUpdateSkeleton(skeletonConfig: config)
         }
-
+        layoutSkeletonIfNeeded()
+        
         if let root = root {
             _flowDelegate?.didUpdateSkeletons(rootView: root)
         }

SkeletonViewCore/Sources/Internal/UIKitExtensions/UIView+Transitions.swift

@@ -5,6 +5,8 @@ import UIKit
 extension UIView {
 
     func startTransition(transitionBlock: @escaping () -> Void) {
+        layoutIfNeeded()
+        
         guard let transitionStyle = _currentSkeletonConfig?.transition,
               transitionStyle != .none else {
             transitionBlock()