Prepare plugin support for objects with multiple BaseTextures (#3830) ...

* Add ability for Prepare plugin to upload the all textures for AnimatedSprites

* Add a new function to loop through all the textures of an AnimatedSprite and add them to the queue
* Moved Duplicate `findBaseTextures` function from WebGL & Canvas Prepare to Base prepare as static
* Moved all the `findObjectType` methods to their appropiate class as static methods for consistency

* Updated Comments to reflect "static" not "private" methods

* Added the findTexturesForAnimatedSprites logic to the standard findBasicTextures

This cleans up the need to worry about ordering the registration of hooks and only calls upload once

* Split the prepare.register function into 2 registerFindHook & registerUploadHook

* Some simple cleanup before the PR

* comment formatting

* removed dependenvy on `extras` from prepare

* Fix small comment issues with pull request

Removed the [optional] reference in the comments for both
new register methods.
Added a small example to the docs

* Add deprecation method

* Added Check before calling hooks and reformatted JSDoc

Lint wouldn't pass without the params in the JSDoc

* added `instanceof` check and fixed up the return true only if a texture is found

Fix preparation of destroyed items (#3802) ...

* Added isDestroyed to DisplayObject, BaseTexture. Don't prepare destroyed items.

* isDestroyed -> _destroyed, marked as private

Added prepare hooks for Text.

Delayed item preparation to do it outside of the RAF call.

Added unit tests for prepare.