[Tizen] Support Brushes to Tizen

[rookiejava]

Description of Change

This PR adds Brushes (#9220) Tizen implementation.

This change also allows the user to choose whether to use the SkiaSharp-based renderer via the init option. Comparing the existing renderers, SkiaSharp-based renderer will bring huge functional advantages including Shapes, Brush, BorderElement and enhancing limited features which has been existed on default renderers.

To enable the SkiaSharp-based renderers, use Forms.Init() as shown below. (The default is false.)

var option = new InitializationOptions(app) { UseSkiaSharp = true }; 
Forms.Init(option);

Currently available SkiaSharp-based renderers are as follows.

• LayoutRenderer (StackLayout, AbsoluteLayout, Grid, ...)
• PageRenderer (ContentPage)
• FrameRenderer
• BoxViewRenderer
• ImageRenderer

Issues Resolved

• fixes (partially) Xamarin.Forms Drawing Spec #2452
• fixes (partially) [Enhancement] Add brush support for background #1856
• fixes (partially) [Spec] Brushes #7293
• fixes [Bug] GradientBrush not working in Tizen #11995

API Changes

namespace Xamarin.Forms
Added:

• bool InitializationOptions.UseSkiaSharp {get; set;}
• bool Forms.UseSkiaSharp {get;}

namespace Xamarin.Forms.Platform.Tizen
Added:

• class BrushExtensions
• SKCanvasView LayoutRenderer.BackgroundCanvas {get;}
• void LayoutRenderer.OnBackgroundPaint()
• void LayoutRenderer.OnBackgroundLayoutUpdated()
• SKCanvasView PageRenderer.BackgroundCanvas {get;}

namespace Xamarin.Forms.Platform.Tizen.SkiaSharp
Added:

• interface IBackgroundCanvas
• abstract class CanvasViewRenderer
• class BoxViewRenderer
• class FrameRenderer
• class ImageRenderer

Platforms Affected

• Tizen

Behavioral/Visual Changes

None

Before/After Screenshots

• StackLayout

• ContentPage

• BoxView

• Frame

• Image

Testing Procedure

Launch Core Gallery and navigate to the new Gradients Gallery.

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[rmarinho]

/azp run

[azure-pipelines]

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