fix viewer build

Fixes an issue I introduced when adding the features functionality. I imported harfbuzz from our text header which causes all downstream users to need to know where the harfbuzz includes are. This isn't necessary and slows down the compiler too.

Diffs=
500d878a2 fix viewer build (#5493)

Co-authored-by: Luigi Rosso <luigi-rosso@users.noreply.github.com>

.rive_head

diff --git a/.rive_head b/.rive_head
index c5fb219..af36ab6 100644
--- a/.rive_head
+++ b/.rive_head
@@ -1 +1 @@
-31d9a54243e694ede76dc133cf209d7b67c13708
+500d878a23cb0f8a5a65aca9ac80d5c79fc92eb6

include/rive/text/font_hb.hpp

diff --git a/include/rive/text/font_hb.hpp b/include/rive/text/font_hb.hpp
index 23b7a11..05e0c1a 100644
--- a/include/rive/text/font_hb.hpp
+++ b/include/rive/text/font_hb.hpp
@@ -7,10 +7,13 @@
 
 #include "rive/factory.hpp"
 #include "rive/text_engine.hpp"
-#include "hb.h"
 
 #include <unordered_map>
 
+struct hb_font_t;
+struct hb_draw_funcs_t;
+struct hb_feature_t;
+
 class HBFont : public rive::Font
 {
 public:
@@ -37,8 +40,8 @@
 
 private:
     HBFont(hb_font_t* font,
-           std::unordered_map<hb_tag_t, float> axisValues,
-           std::unordered_map<hb_tag_t, uint32_t> featureValues,
+           std::unordered_map<uint32_t, float> axisValues,
+           std::unordered_map<uint32_t, uint32_t> featureValues,
            std::vector<hb_feature_t> features);
 
     // If the platform can supply fallback font(s), set this function pointer.
@@ -60,10 +63,10 @@
     hb_draw_funcs_t* m_drawFuncs;
 
     // Feature value lookup based on tag.
-    std::unordered_map<hb_tag_t, uint32_t> m_featureValues;
+    std::unordered_map<uint32_t, uint32_t> m_featureValues;
 
     // Axis value lookup based on for the feature.
-    std::unordered_map<hb_tag_t, float> m_axisValues;
+    std::unordered_map<uint32_t, float> m_axisValues;
 };
 
 #endif