core: Defer WebGPU dynamic texture wrapper creation (#4369)

include/mbgl/gfx/dynamic_texture.hpp

@@ -65,8 +65,11 @@ public:
     virtual bool removeTexture(const TextureHandle& texHandle);
 
 protected:
+    DynamicTexture(Size size, TexturePixelType pixelType);
+
     mapbox::ShelfPack shelfPack;
     Texture2DPtr texture;
+    TexturePixelType pixelFormat;
     int numTextures = 0;
     std::mutex mutex;
 };

include/mbgl/webgpu/dynamic_texture.hpp

@@ -19,6 +19,9 @@ public:
         std::unordered_map<gfx::TextureHandle, std::unique_ptr<uint8_t[]>, gfx::TextureHandle::Hasher>;
 
 private:
+    Context& context;
+    Size size;
+    gfx::TexturePixelType pixelType;
     bool deferredCreation = false;
     ImagesToUpload imagesToUpload;
 };