Provides access to GDExtension functionality. The GDExtensionManager loads, initializes, and keeps track of all available [GDExtension] libraries in the project. [b]Note:[/b] Do not worry about GDExtension unless you know what you are doing. $DOCS_URL/tutorials/scripting/gdextension/what_is_gdextension.html $DOCS_URL/tutorials/scripting/gdextension/gdextension_cpp_example.html Returns the [GDExtension] at the given file [param path], or [code]null[/code] if it has not been loaded or does not exist. Returns the file paths of all currently loaded extensions. Returns [code]true[/code] if the extension at the given file [param path] has already been loaded successfully. See also [method get_loaded_extensions]. Loads an extension by absolute file path. The [param path] needs to point to a valid [GDExtension]. Returns [constant LOAD_STATUS_OK] if successful. Reloads the extension at the given file path. The [param path] needs to point to a valid [GDExtension], otherwise this method may return either [constant LOAD_STATUS_NOT_LOADED] or [constant LOAD_STATUS_FAILED]. [b]Note:[/b] You can only reload extensions in the editor. In release builds, this method always fails and returns [constant LOAD_STATUS_FAILED]. Unloads an extension by file path. The [param path] needs to point to an already loaded [GDExtension], otherwise this method returns [constant LOAD_STATUS_NOT_LOADED]. Emitted after the editor has finished reloading one or more extensions. The extension has loaded successfully. The extension has failed to load, possibly because it does not exist or has missing dependencies. The extension has already been loaded. The extension has not been loaded. The extension requires the application to restart to fully load.