[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

2 files changed, 5 insertions, 7 deletions

diff --git a/src/mbgl/text/shaping.cpp b/src/mbgl/text/shaping.cpp
index b43ba0220c..e68566d419 100644
--- a/src/mbgl/text/shaping.cpp
+++ b/src/mbgl/text/shaping.cpp
@@ -3,16 +3,15 @@
 
 namespace mbgl {
 
-PositionedIcon shapeIcon(const SpriteAtlasElement& image,
-                         const SymbolFeature& feature) {
-    float dx = feature.iconOffset[0];
-    float dy = feature.iconOffset[1];
+PositionedIcon shapeIcon(const SpriteAtlasElement& image, const std::array<float, 2>& iconOffset, const float iconRotation) {
+    float dx = iconOffset[0];
+    float dy = iconOffset[1];
     float x1 = dx - image.spriteImage->getWidth() / 2.0f;
     float x2 = x1 + image.spriteImage->getWidth();
     float y1 = dy - image.spriteImage->getHeight() / 2.0f;
     float y2 = y1 + image.spriteImage->getHeight();
 
-    return PositionedIcon(image, y1, y2, x1, x2, feature.iconRotation);
+    return PositionedIcon(image, y1, y2, x1, x2, iconRotation);
 }
 
 } // namespace mbgl
diff --git a/src/mbgl/text/shaping.hpp b/src/mbgl/text/shaping.hpp
index b0e6ae3b1d..1b7b8b2733 100644
--- a/src/mbgl/text/shaping.hpp
+++ b/src/mbgl/text/shaping.hpp
@@ -36,7 +36,6 @@ public:
     explicit operator bool() const { return image && (*image).pos.hasArea(); }
 };
 
-PositionedIcon shapeIcon(const SpriteAtlasElement&,
-                         const SymbolFeature&);
+PositionedIcon shapeIcon(const SpriteAtlasElement&, const std::array<float, 2>& iconOffset, const float iconRotation);
 
 } // namespace mbgl