SwipeView + Widget + Extensions

[edgarfgp]

This PR adds support for SwipeView based on https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/swipeview

SwipeView(
      (Grid() {
          Label("Swipe left or Right")
              .centerTextHorizontal ()
       })
          .centerHorizontal()
          .centerVertical()
          .size(300., 60.)
          .backgroundColor (Xamarin.Forms.Color.LightGray)
  ).leftItems(
      SwipeItems() {
          SwipeItem(AboutTapped)
              .text("About")
              .backgroundColor(Xamarin.Forms.Color.Red)
              .iconImageSource ("favoritetab.png")

          SwipeItem(AboutTapped)
              .text("About")
              .backgroundColor(Xamarin.Forms.Color.Green)
              .iconImageSource ("alltab.png")

          SwipeItem(AboutTapped)
              .text("github")
              .iconImageSource ("xamarin.png")
      }
  ).onSwipeStarted(SwipeStarted)

https://user-images.githubusercontent.com/31915729/159030437-509342ab-a2dc-4826-a73d-de9113c820d2.mp4

[edgarfgp]

@TimLariviere . There seems be a conflict in the due to the doc updates. as my branch was not update before I raised a PR Do you mind fixing them ?

[TimLariviere]

Ah yes, sorry. You got caught in my tests for setting up a documentation website 😅 I'll fix that