Added IndicatorsView (#7465)

Added IndicatorsView  (#7465)

* Added IndicatorsView

* removed static ctor

* refused plural in naming

* opened ItemsSource property

* followed code convention

* renamed IndicatorView (removed plural)

* made Color.Default as initial value

* updated IndicatorSize initial value

* Added IndicatorViewExtensions

* naming changes

* fix build

* small cleanup

* refactored control to templatedView

* added UIPageControl renderer for iOS

* moved extensions class to separate file

* removed useless private methods

* local vars name refactoring

* tapGesture naming update

* avoided linq

* code styling

* fixed default indicator colors for iOS

* added experimental flag

* [Core]Update api naming for IndicatorView

* Update IndicatorView.cs

* [Core] Add forms visual

* Revert "[Core] Add forms visual"

This reverts commit 380f36684ebf1d90ce8df074c13f70f8549ba8db.

* Revert "Revert "[Core] Add forms visual""

This reverts commit 6619e9e758970de3c11672ed2fb181dc37fe6ad0.

* [Gallery]Revert changes to gallery

* [Android] Export default renderer for FormsVisual

* [iOS] Handle FormsVisual for IndicatorView

* [iOS] Update Position from native renderer

* [iOS] IndicatorVIewRendederer updates and dispose

* [Controls] Fix merge

* Added IndicatorView Core Gallery sample

* Add  IndicatorSample

* Update Xamarin.Forms.Controls.csproj

* [Core] Fix FormsVisual check

* [iOS] Fix FormsVisual check

* [Controls] Fix Indicator Gallery sample

* [Core] Cleanup IndicatorView

* [Core]Fix toogle between template and shapes on FormsVisual

* [Controls] Fix indicators samples

* [Controls] Fix IndicatorTemplate

* [Core] Add ItemsSourceBy xaml option

* [iOS,Android,Core] Add IndicatorStacklayout

* [Android] Remove extra renderer for FormsVisual

* [Controls] Remove Visual from Indicator sample

* [Core, iOS, Android] Fix bug on IndcatorView

* - remove forms visual

* - remove extra shared

* - remove forms visual

* - remove disposable

* - remove renderer from tizen