Add easy option to toggle business listings at zoom 15+

[nvkelso]

In the v3 schema we introduce many more business listing POIs at zoom 15+ (earlier in the data, later in the style). Right now they are text only labels, but soon they could also include artwork icons.

We could consider a config option to:

• Show these new POIs at later zoom than 15
• Disable them completely

This would reduce the visual noise at this zoom – which is now more comparable to Apple Maps or Google Maps while before it was more for a pure data viz use case.

[bdon]

In thinking about the "control plane" for the style library, the parameters are basically

1. light/dark/monochrome mode
2. nolabels layers, labels layers (for sandwiches), or labels-only (for overlays)
3. localized display language, or even two

Stretch ideas

1. label density
2. contrast
3. POI density ("detail")

See label and detail parameters at https://tangrams.github.io/refill-style/#15/37.7926/-122.4003