Is your feature request related to a problem? Please describe.

I need to do some custom rendering with framebuffer and texture and then display it via eframe, but eframe doesn't provide a way to convert the native texture id to epaint::TextureId.

I've found Painter::register_native_texture but I can't access it through eframe.

Describe the solution you'd like

1. Pass the &mut Painter to the user to be able to register the native texture
2. Provide a function that allows the user to register a native texture.

Describe alternatives you've considered

None.

Additional context

None.