Add data converters to flutter runtime

It's the dart implementation of the first converters.
It's very similar to the c++ implementation.
Except some commented details of this PR, the rest is basically the same.

Diffs=
727e0ba8b Add data converters to flutter runtime (#8029)

Co-authored-by: hernan <[email protected]>

.rive_head

@@ -1 +1 @@
-f25ee97a05aaa30a58b13451c8020c4e1c095bed
+727e0ba8b098d87dfa5d32ce3004c619659a81e0

include/rive/animation/state_machine_instance.hpp

@@ -170,6 +170,7 @@ class StateMachineInstance : public Scene, public NestedEventNotifier, public Ne
 #ifdef WITH_RIVE_TOOLS
 public:
     void onInputChanged(InputChanged callback) { m_inputChangedCallback = callback; }
+    void onDataBindChanged(DataBindChanged callback);
     InputChanged m_inputChangedCallback = nullptr;
 #endif
 };

include/rive/data_bind/data_bind.hpp

@@ -10,7 +10,6 @@
 #include <stdio.h>
 namespace rive
 {
-
 #ifdef WITH_RIVE_TOOLS
 class DataBind;
 typedef void (*DataBindChanged)();
@@ -38,6 +37,11 @@ class DataBind : public DataBindBase
     std::unique_ptr<DataBindContextValue> m_ContextValue;
     DataConverter* m_dataConverter;
     DataType outputType();
+#ifdef WITH_RIVE_TOOLS
+public:
+    void onChanged(DataBindChanged callback) { m_changedCallback = callback; }
+    DataBindChanged m_changedCallback = nullptr;
+#endif
 };
 } // namespace rive
 

src/animation/state_machine_instance.cpp

@@ -1004,6 +1004,16 @@ StateMachineInstance::~StateMachineInstance()
     m_bindablePropertyInstances.clear();
 }
 
+#ifdef WITH_RIVE_TOOLS
+void StateMachineInstance::onDataBindChanged(DataBindChanged callback)
+{
+    for (auto databind : m_dataBinds)
+    {
+        databind->onChanged(callback);
+    }
+}
+#endif
+
 void StateMachineInstance::sortHitComponents()
 {
     Drawable* last = m_artboardInstance->firstDrawable();

src/data_bind/data_bind.cpp

@@ -187,5 +187,11 @@ bool DataBind::addDirt(ComponentDirt value, bool recurse)
     }
 
     m_Dirt |= value;
+#ifdef WITH_RIVE_TOOLS
+    if (m_changedCallback != nullptr)
+    {
+        m_changedCallback();
+    }
+#endif
     return true;
 }