message: add .visuals to PlyProvider
diff: import { StateTransforms } from '../transforms';
  import { DataFormatProvider } from './provider';
  +import { PluginContext } from '../../mol-plugin/context';
  +import { StateObjectRef } from '../../mol-state';
  +import { PluginStateObject } from '../objects';
  const Category = 'Shape';
  @@ -25,6 +28,12 @@ export const PlyProvider = DataFormatProvider({
  await format.commit();
  return { format: format.selector, shape: shape.selector };
  + },
  + visuals(plugin: PluginContext, data: { shape: StateObjectRef<PluginStateObject.Shape.Provider> }) {
  + const repr = plugin.state.data.build()
  + .to(data.shape)
  + .apply(StateTransforms.Representation.ShapeRepresentation3D);
  + return repr.commit();
  }
  });
  