Derive Var and Export for DynGd<T, D>

- Rename test class from `RefcGdExporter` to `RefcDynGdExporter`

godot-core/src/registry/class.rs

@@ -352,10 +352,10 @@ pub(crate) fn try_dynify_object<T: GodotClass, D: ?Sized + 'static>(
     Err(error.into_error(object))
 }
 
-/// Responsible for creating hint_string for [`DynGd<T, D>`][crate::obj::DynGd] properties that works with [`PropertyHint::NODE_TYPE`][crate::global::PropertyHint::NODE_TYPE] or [`PropertyHint::RESOURCE_TYPE`][crate::global::PropertyHint::RESOURCE_TYPE].
+/// Responsible for creating hint_string for [`DynGd<T, D>`][crate::obj::DynGd] properties which works with [`PropertyHint::NODE_TYPE`][crate::global::PropertyHint::NODE_TYPE] or [`PropertyHint::RESOURCE_TYPE`][crate::global::PropertyHint::RESOURCE_TYPE].
 ///
 /// Godot offers very limited capabilities when it comes to validating properties in the editor if given class isn't a tool.
-/// Proper hint string combined with `PropertyHint::NODE_TYPE` or `PropertyHint::RESOURCE_TYPE` allows to limit selection only to valid classes - this being the ones registered as implementors of given `DynGd<T, D>`'s `D` trait.
+/// Proper hint string combined with `PropertyHint::NODE_TYPE` or `PropertyHint::RESOURCE_TYPE` allows to limit selection only to valid classes - those registered as implementors of given `DynGd<T, D>`'s `D` trait.
 ///
 /// See also [Godot docs for PropertyHint](https://docs.godotengine.org/en/stable/classes/[email protected]#enum-globalscope-propertyhint).
 pub(crate) fn get_dyn_property_hint_string<D>() -> GString

itest/godot/ManualFfiTests.gd

@@ -69,7 +69,7 @@ func test_export():
 	node.free()
 
 func test_export_dyn_gd():
-	var dyn_gd_exporter = RefcGdExporter.new()
+	var dyn_gd_exporter = RefcDynGdExporter.new()
 
 	# NodeHealth is valid candidate both for `empty` and `second` fields.
 	var node = NodeHealth.new()
@@ -86,7 +86,7 @@ func test_export_dyn_gd():
 	node.free()
 
 func test_export_dyn_gd_should_fail_for_wrong_type():
-	var dyn_gd_exporter = RefcGdExporter.new()
+	var dyn_gd_exporter = RefcDynGdExporter.new()
 	var refc = RefcHealth.new()
 
 	disable_error_messages()

itest/rust/src/object_tests/dyn_gd_test.rs

@@ -451,7 +451,7 @@ impl InstanceIdProvider for foreign::NodeHealth {
 
 #[derive(GodotClass)]
 #[class(init)]
-struct RefcGdExporter {
+struct RefcDynGdExporter {
     #[var]
     first: Option<DynGd<Object, dyn Health>>,
     #[export]