Move SkiaGpuContext creation in SkiaVkRenderEngine to virtual function

Making GaneshVkRenderEngine / GraphiteVkRenderEngine handle this reduces
the need for higher-level branching.

Test: boots successfully with skiavkthreaded
Bug: b/293371537
Change-Id: I5685cb9dd7b0dc1ce3a2d538a729c255fbd6c52b
diff --git a/libs/renderengine/skia/GaneshVkRenderEngine.h b/libs/renderengine/skia/GaneshVkRenderEngine.h
index 86fa384..5940d04 100644
--- a/libs/renderengine/skia/GaneshVkRenderEngine.h
+++ b/libs/renderengine/skia/GaneshVkRenderEngine.h
@@ -27,6 +27,7 @@
 protected:
     GaneshVkRenderEngine(const RenderEngineCreationArgs& args) : SkiaVkRenderEngine(args) {}
 
+    std::unique_ptr<SkiaGpuContext> createContext(VulkanInterface& vulkanInterface) override;
     void waitFence(SkiaGpuContext* context, base::borrowed_fd fenceFd) override;
     base::unique_fd flushAndSubmit(SkiaGpuContext* context, sk_sp<SkSurface> dstSurface) override;
 };