'queryRenderedSymbols' mixes results from different sources

[ChrisLoer]

Another bug discovered in the native port of #5150...

In CollisionIndex#queryRenderedSymbols, we filter results to match the tile of the FeatureIndex doing the querying:

https://github.com/mapbox/mapbox-gl-js/blob/master/src/symbol/collision_index.js#L255

We also need to filter based on the source -- otherwise we'll return results from multiple sources as long as they're on the same tile. The results are in the form of an index into a tile/source-specific collision array, so what will actually get returned after the array lookup is pretty much undefined.

I think the fix here is:

• Store the source ID of everything in the collision grid, along with the tile ID
• Use the source ID in the query to filter results

Needs a two-source query test.

/cc @ansis @anandthakker