Add static method to get godot-cpp version from GDScript (#64)

src/GDExtensionTemplate.cpp

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: Unlicense
 
 #include "godot_cpp/core/class_db.hpp"
+#include "godot_cpp/core/version.hpp"
 
 #include "GDExtensionTemplate.h"
 #include "Version.h"
@@ -24,9 +25,27 @@ godot::String GDExtensionTemplate::version()
     return VersionInfo::VERSION_STR.data();
 }
 
+/*!
+@brief Get the godot-cpp version string for this extension.
+
+@details
+The version string is generated using godot-cpp's core/version.hpp.
+
+@return The version string (e.g. "godot-cpp v4.2.0-stable").
+*/
+godot::String GDExtensionTemplate::godotCPPVersion()
+{
+    return "godot-cpp v" + godot::uitos( GODOT_VERSION_MAJOR ) + "." +
+           godot::uitos( GODOT_VERSION_MINOR ) + "." + godot::uitos( GODOT_VERSION_PATCH ) + "-" +
+           GODOT_VERSION_STATUS;
+}
+
 /// Bind our methods so GDScript can access them.
 void GDExtensionTemplate::_bind_methods()
 {
     godot::ClassDB::bind_static_method( "GDExtensionTemplate", godot::D_METHOD( "version" ),
                                         &GDExtensionTemplate::version );
+    godot::ClassDB::bind_static_method( "GDExtensionTemplate",
+                                        godot::D_METHOD( "godot_cpp_version" ),
+                                        &GDExtensionTemplate::godotCPPVersion );
 }

src/GDExtensionTemplate.h

@@ -14,6 +14,7 @@ class GDExtensionTemplate : public godot::Object
 
 public:
     static godot::String version();
+    static godot::String godotCPPVersion();
 
 private:
     static void _bind_methods();