transform.coveringTiles support `renderWorldCopies` option

Nobody has claimed this yet.

I noticed that this method has added relevant types in [coveringTiles](https://github.com/mapbox/mapbox-gl-js/blob/37624d45b7185d5a213b8a5cd094ed95a9eb49d4/src/geo/transform.js#L932), but it has not been implemented logically. It only needs to be modified [L1144](https://github.com/mapbox/mapbox-gl-js/blob/37624d45b7185d5a213b8a5cd094ed95a9eb49d4/src/geo/transform.js#L1144)

```js
const renderWorldCopies = options.renderWorldCopies !== undefined ? options.renderWorldCopies : this.renderWorldCopies;

if (renderWorldCopies) {
// Render copy of the globe thrice on both sides
for (let i = 1; i <= NUM_WORLD_COPIES; i++) {
stack.push(newRootTile(-i));
stack.push(newRootTile(i));
}
}
```

this is very useful for implementing some custom rendering externally. If possible, I can submit a PR

Start in src/geo/transform.js at coveringTiles, especially the referenced area around line 1144, and read how the existing renderWorldCopies state is used. Verify that the method respects the renderWorldCopies option supplied by callers, and confirm that custom rendering receives the expected world copies.

Written by the indexing model from the issue text.