move flutter_filament plugin to federated structure

flutter_filament_federated/flutter_filament/windows/egl_context.h

@@ -0,0 +1,36 @@
+#ifndef _EGL_CONTEXT_H
+#define _EGL_CONTEXT_H
+
+#include <Windows.h>
+
+#include <flutter/method_channel.h>
+#include <flutter/plugin_registrar_windows.h>
+#include <flutter/standard_method_codec.h>
+#include <flutter/texture_registrar.h>
+
+#include "flutter_angle_texture.h"
+#include "backend/platforms/PlatformEGL.h"
+#include "flutter_render_context.h"
+
+namespace flutter_filament {
+
+class FlutterEGLContext : public FlutterRenderContext {
+public:
+  FlutterEGLContext(flutter::PluginRegistrarWindows* pluginRegistrar, flutter::TextureRegistrar* textureRegistrar);
+  void* GetSharedContext();    
+  void RenderCallback();
+  void* GetPlatform();
+  void CreateRenderingSurface(uint32_t width, uint32_t height, std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result, uint32_t left, uint32_t top );
+
+private:
+  void* _context = nullptr;
+  EGLConfig _eglConfig = NULL;
+  EGLDisplay _eglDisplay = NULL;
+  ID3D11Device* _D3D11Device = nullptr;
+  ID3D11DeviceContext* _D3D11DeviceContext = nullptr;
+  filament::backend::Platform* _platform = nullptr;
+};
+
+}
+
+#endif