message: fix sprite dispose method
diff: import { Point2d, Point3d, Vector3d, XYAndZ } from "@bentley/geometry-core";
  import { Viewport } from "./Viewport";
  import { DecorateContext } from "./ViewContext";
  -import { IDisposable } from "@bentley/bentleyjs-core/lib/Disposable";
  +import { IDisposable, dispose, Logger } from "@bentley/bentleyjs-core";
  import { RenderTexture, ImageSource, ImageSourceFormat } from "@bentley/imodeljs-common";
  import { IModelApp } from "./IModelApp";
  import { IModelConnection } from "./IModelConnection";
  -import { Logger } from "@bentley/bentleyjs-core";
  import { ImageUtil } from "./ImageUtil";
  /**
  @@ -40,7 +39,7 @@ export class Sprite implements IDisposable {
  public texture?: RenderTexture;
  /** Dispose of this Sprite. Disposes of texture, if present. */
  - public dispose() { if (this.texture) { this.texture.dispose(); this.texture = undefined; } }
  + public dispose() { this.texture = dispose(this.texture); }
  /** Initialize this sprite from a .png file located in the imodeljs-native assets directory.
  * @param filePath The file path of the PNG file holding the sprite texture (relative to the assets directory.)
  