Manually created batches can't be destroyed using BatchManager

[OlegGedzjuns]

Description

It is possible to manually prepare and create batches using BatchManager prepare() and create() methods.
BatchManager also has destroyBatch() method, but calling it with a manually created batch causes a crash.

Link to example: https://playcanvas.com/project/1295595/overview/manual-batching-issue

Also according to destroy method implementation, batches from _batchList array are never removed.

engine/src/scene/batching/batch-manager.js

Line 927 in 9e277aa

destroyBatch(batch) {

[mvaligursky]

you should call batch.destroy instead of private batcher.destroyBatch.
I just made it public.

        //this.app.batcher.destroyBatch(batch);
        batch.destroy(this.app.scene, [pc.LAYERID_WORLD]);

[OlegGedzjuns]

Yes, it is possible to use batch.destroy() method. But destroyed batches are still in the _batchList array.
Example project was updated to use dynamic batches so now you can see the issue more clearly.