Fixed layer management in Direct2D renderer.

ID2D1RenderTarget::PushAxisAlignedClip/PopAxisAlignedClip used to clip the region (with wxGraphicsRenderer::Clip) and ID2D1RenderTarget::PushLayer/PopLayer used to rendering to the transparent layer (with wxGraphicsRenderer::BeginLayer) are non independent but have to be used in the controlled sequences: "A PushAxisAlignedClip and PopAxisAlignedClip pair can occur around or within a PushLayer and PopLayer, but cannot overlap" (and of course finally each Push* call must have a matching Pop* call).
To control the sequence of access to the AxisAlignedClips and Layers there is implemented a wxStack data member holding Clips/Layers parameters which reflects a physical stack of respective Clips/Layers in ID2D1RenderTarget. This way we know in which order to pop and what to pop from ID2D1RenderTarget stack if there is a need to do so.

Closes #17590

interface/wx/graphics.h

@@ -451,12 +451,24 @@ public:
     static wxGraphicsContext* Create();
 
     /**
-        Clips drawings to the specified region.
+        Sets the clipping region to the intersection of the given region
+        and the previously set clipping region.
+        The clipping region is an area to which drawing is restricted.
+
+        @remarks
+        - Calling this function can only make the clipping region smaller,
+        never larger.
+
+        - You need to call ResetClip() first if you want to set the clipping
+        region exactly to the region specified.
+
+        - If resulting clipping region is empty, then all drawing upon the context
+        is clipped out (all changes made by drawing operations are masked out).
     */
     virtual void Clip(const wxRegion& region) = 0;
 
     /**
-        Clips drawings to the specified rectangle.
+        @overload
     */
     virtual void Clip(wxDouble x, wxDouble y, wxDouble w, wxDouble h) = 0;