Allow 'feature-state' expressions on 'layout' or 'filter' properties

[jonshutt]

Motivation

With a large dataset, we can dynamically use setFeatureState to change some aspects of how a feature is displayed without having to update the entire geojson source. However, this only works with the 'Paint' property.

paint: { 'icon-opacity': ['case', ['boolean', ['feature-state', 'filtered'], false], 1,.5], },

This works well, but we can't use it for things like text-size, or visibility that are handled in the 'paint' property.

Mock-Up

{ layout: { 'visibility': ['case', ['boolean', ['feature-state', 'filtered'], false], 'visible', 'none'], }

Concepts

setFeatureState doesn't change, it's already setting data agnostic to how it will be used
Allowing layout and filters to use 'feature-state' standardises which option work between paint, filter, and layout

Implementation