* WIP
* WIP
* WIP
* Remove Filter::operator()(const Feature&)
* WIP
* WIP
* WIP
* WIP
* Hook up expression filter evaluator
* Replace `shared_ptr` with &reference
* Fill in implementation of `void operator()(const ExpressionFilter&)`
* Fix failing tests
* Switch back to a shared_ptr per chat with @anandthakker
* Fix benchmark compilation
* Shot in the dark to fix CI
* Shot in the dark to fix CI (part 2)
* Shot in the dark to fix CI (part 3)
* In src/mbgl/style/conversion/filter.cpp, add a port of isExpressionFilter and use it to decide in Converter<Filter>::operator() whether to parse the incoming JSON as an ExpressionFilter or one of the legacy filter types
* Remove bool Filter::operator()(const GeometryTileFeature&) const
* Ensure the map zoom is passed into filtering operations wherever applicable
* Add expression filter tests
* Addressed PR feedback
* Implement `NSPredicate *operator()(mbgl::style::ExpressionFilter filter)`
* Fix formatting& nit
