Enable clustering using View Annotation

[YoungjunGu]

New Feature

Hello, I would like to request the development of the clustering function.

When using PointAnnotation or SymbolAnnotation, there is a cluster option in the source, so we implemented the clustering function by referring to the example or Doc you wrote. we need the clustering function when I use Custom View Annotation, so is it possible to develop it additionally?

• connected issue(android): https://github.com/mapbox/mapbox-maps-android/issues/1940

Why

• To implement clustering capabilities using CustomViewAnnotation
• connected issue: https://github.com/mapbox/mapbox-maps-ios/issues/1985