A way to determine if features are loading in the tileset

[michalgwo]

Is your feature request related to a problem? Please describe.
When zooming in, new data is being loaded, but there is no way to determine in code if it's loading and when loading is finished. Let's say I have data in my tiles starting from zoom 14. Assuming the app is just opened and data was not loaded previously, when I zoom to 14, and immediately call vectorSource.querySourceFeatures(), it will return an empty list.

Describe the solution you'd like
A function determining if data is loading, for example vectorSource.isDataLoading()

Describe alternatives you've considered
I tried to check style.isFullyLoaded before source.querySourceFeatures(), but it returns true even if the data is loading.