introduces new apis and extensions for more convenience and ease of use

[EudyContreras]

Whats new 🎉

New functions, properties and extensions for easier use:

• New for ViewGroups ✨

  fun ViewGroup.enableSkeletonLoading(): SkeletonDrawable?
  fun ViewGroup.disableSkeletonLoading(): SkeletonDrawable?
  fun ViewGroup.toggleSkeletonLoading(enabled: Boolean): SkeletonDrawable?

• New for SkeletonBuilders ✨

  val properties: SkeletonProperties
  fun get(): SkeletonDrawable

• New for SkeletonBuilders ✨

  val properties: BoneProperties
  fun get(): BoneDrawable

• New for BoneDrawables ✨

  fun disable()
  fun enable(view: View)

• New for SkeletonDrawables ✨

  fun disable()
  fun enable(view: ViewGroup)