Add style image missing binding integration

[tobrun]

closes #14319, refs core integration in #14253 and iOS integration in #14302.

• add java public api
• add c++ integration
• add test around sample
• integrate small example in test app

[LukasPaczos]

Looks great, just a couple of questions and nitpicks.

[tobrun]

To resolve multiple callback invocations, I looked into profiling the usefulness of back grounding the image conversions. Test were performed with simple map activity and adding 20 images to the style. The profiler for CPU and memory didn't really show an actionable difference. The execution time of non async addition of images was faster for the map to become idle.

The GPU profiler does show a small difference, you can see that the third bar in the images below is higher for the async variant as there is overhead created by the 20 asynctasks.

When using the addImages overload that only spawns 1 asycntask for 20 images, the results are not improved.

Atm, not seeing an actual evidence that the background conversion is actually usefull.

[LukasPaczos]

🤔 What device did you use for testing? High-end devices might disguise the slowdown.

[tobrun]

Nokia 1	sync	async
Style#addImages
Style#addImage

[tobrun]

Capturing from chat, moving forward with both exposing synchronous as asynchronous addImage overloads on Style. With this in place no additional bookkeeping is required to use the image missing callback.