[core] Implement data-driven styling for {text,icon}-{color,opacity,halo-color,halo-blur,halo-width} (#7939)

* Add symbol dds attributes and adapt style code generation

* Update to mapbox-gl-js/master

* Refactor SymbolFeature as a subclass of GeometryTileFeature

Prepares for enabling DDS on symbol paint properties by allowing the
SymbolFeatures, which we keep around after constructing SymbolLayout,
to be used in evaluating data-driven paint properties later in the
layout process.

* Draft approach for splitting icon/text paint properties

The `Program` types are set up to bind GL attributes to each of the
data-driven paint properties specified in the `PaintProperties` type
provided.  Since `SymbolPaintProperties` specifies both `Text*` and
`Icon*` properties, the symbolIcon, symbolIconSDF, and symbolGlyph
programs each attempt to bind roughly double the number of attributes
that they actually need.

This change addresses this by:
- Adding the more specific `IconPaintProperties` and `TextPaintProperties` types, which are subsets of the full `SymbolPaintProperties`.
- The symbol layer continues to use its `SymbolPaintProperties paint` member to track layer property state, but it provides helpers that construct objects of each the specific `{Icon,Text}PaintProperties::Evaluated` type, for use by the painter.
- The three symbol programs instantiate `Program<>` using the appropriate `{Icon,Text}PaintProperties` type.

* check in generated style code

* Populate paint buffers for symbol DDS properties

* Address first round of review comments

* Refactor VectorTile{Layer,Feature} to explicitly share data

* Update submodule

1 files changed, 10 insertions, 10 deletions

diff --git a/src/mbgl/style/layers/symbol_layer_properties.hpp b/src/mbgl/style/layers/symbol_layer_properties.hpp
index 3bdae377ea..f2b7bfa00f 100644
--- a/src/mbgl/style/layers/symbol_layer_properties.hpp
+++ b/src/mbgl/style/layers/symbol_layer_properties.hpp
@@ -180,23 +180,23 @@ struct TextOptional : LayoutProperty<bool> {
     static bool defaultValue() { return false; }
 };
 
-struct IconOpacity : PaintProperty<float> {
+struct IconOpacity : DataDrivenPaintProperty<float, attributes::a_opacity> {
     static float defaultValue() { return 1; }
 };
 
-struct IconColor : PaintProperty<Color> {
+struct IconColor : DataDrivenPaintProperty<Color, attributes::a_fill_color> {
     static Color defaultValue() { return Color::black(); }
 };
 
-struct IconHaloColor : PaintProperty<Color> {
+struct IconHaloColor : DataDrivenPaintProperty<Color, attributes::a_halo_color> {
     static Color defaultValue() { return {}; }
 };
 
-struct IconHaloWidth : PaintProperty<float> {
+struct IconHaloWidth : DataDrivenPaintProperty<float, attributes::a_halo_width> {
     static float defaultValue() { return 0; }
 };
 
-struct IconHaloBlur : PaintProperty<float> {
+struct IconHaloBlur : DataDrivenPaintProperty<float, attributes::a_halo_blur> {
     static float defaultValue() { return 0; }
 };
 
@@ -208,23 +208,23 @@ struct IconTranslateAnchor : PaintProperty<TranslateAnchorType> {
     static TranslateAnchorType defaultValue() { return TranslateAnchorType::Map; }
 };
 
-struct TextOpacity : PaintProperty<float> {
+struct TextOpacity : DataDrivenPaintProperty<float, attributes::a_opacity> {
     static float defaultValue() { return 1; }
 };
 
-struct TextColor : PaintProperty<Color> {
+struct TextColor : DataDrivenPaintProperty<Color, attributes::a_fill_color> {
     static Color defaultValue() { return Color::black(); }
 };
 
-struct TextHaloColor : PaintProperty<Color> {
+struct TextHaloColor : DataDrivenPaintProperty<Color, attributes::a_halo_color> {
     static Color defaultValue() { return {}; }
 };
 
-struct TextHaloWidth : PaintProperty<float> {
+struct TextHaloWidth : DataDrivenPaintProperty<float, attributes::a_halo_width> {
     static float defaultValue() { return 0; }
 };
 
-struct TextHaloBlur : PaintProperty<float> {
+struct TextHaloBlur : DataDrivenPaintProperty<float, attributes::a_halo_blur> {
     static float defaultValue() { return 0; }
 };