7267: ScrollBar sample

not finish!
7268
7270: drag sample
7271:
7272: move Demo to DemoList

use reflection technique for each demo
7273: update scrollbar sample
7281: scrollbar not complete
7283: UIScrollView sample

add UIScrollView sample,
UIPanel , Viewport Support
UIScrollRelation bind scrollbar and ScrollView
7284: update IParentLink
7285: VisualLayer.OwnerRenderElement
7288: merge GridLayer to MiniUI
7289: GridTable

not finished
7290: add GridTable impl detail
7297: update GridSample
7299: GridLayer
7301: UIListView sample
 7305: merge TextLayer and Text

update ctor of TextSpan
7313: Caret Revisit

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7314: MyIntervalTaskEventArgs
7316: textEditBox.SwapCaretState