Bobbing map pin icon SymbolLayer example

[langsmith]

Good example to add would be a map pin icon bobbing up and down. Could be done with a runnable that constantly adjusts the iconTranslate() PropertyFacotry method, similar to how the loading circle radius is adjusted in the demo app's Mapillary example

https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/labs/SymbolLayerMapillaryActivity.java#L256

https://github.com/mapbox/mapbox-android-demo/blob/master/MapboxAndroidDemo/src/main/java/com/mapbox/mapboxandroiddemo/examples/labs/SymbolLayerMapillaryActivity.java#L983-L1010

[langsmith]

Although the pins don't bob in #934, #934 will resolve this ticket in my opinion. The example shows how runnables can be combined with data-driven styling (iconTranslate in particular) to adjust icon location however one would like.