Support For Multi-Image Sources + Raster Layers

Nobody has claimed this yet.

## Motivation
Mapbox currently supports an `image` source + `raster` layer, which can display a single image over a map. For example: https://docs.mapbox.com/mapbox-gl-js/example/image-on-a-map/

If you were to build a real world application with the above though, you would need a separate `image` source & `raster` layer for every single image, which quickly becomes unmanageable (and presumably, bad for performance).

Some use cases:
- Adding building interior raster images
- Adding weather pattern overlays
- Adding custom captured drone satellite imagery

Often it isn't possible or performant to create a full tile raster layer for the above use cases, and there would be many "holes" in the map (e.g. for building interiors)

## Design Alternatives
- Adding an image source + raster layer for every single image (messy + likely impacts performance)
- Building a complete raster tile layer by combining all images into one (non-performant in case layer has many holes/gaps + requires overhead to regenerate all tiles every time a new image is added)

## Design

Not knowing anything about Mapbox internals, I can't really suggest an implementation, but from an API consumer perspective, something like the below would be ideal:

```
map.addSource('radar', {
'type': 'image',
'images': [{
'url': 'https://docs.mapbox.com/mapbox-gl-js/assets/radar.gif',
'coordinates': [
[-80.425, 46.437],
[-71.516, 46.437],
[-71.516, 37.936],
[-80.425, 37.936]
]
}]
});
```

And being able to display the `radar` source in a single raster layer like below:

```
map.addLayer({
id: 'radar-layer',
'type': 'raster',
'source': 'radar',
'paint': {
'raster-fade-duration': 0
}
});
```

No implementation files or tests are named. Start by tracing the existing image source and raster layer entry points behind the linked image-on-a-map example; done means one image source accepts multiple images and a single raster layer displays them as proposed.

Written by the indexing model from the issue text.