The VCS interface can be thought of like a proxy system, where any call
to the API is redirected to the actual implementation of the VCS API
which may be existing in the form of a GDNative plugin which is marked
as a singleton and is not marked reloadable. If the implementation
doesn't exist in the file system, it only returns the default responses which contain
mostly empty containers of the data type that every API call returns.
EditorVCSInterface is used like a Godot object with a script attached to it. The script
is the implementation of the API and the object is the interface to the
script, which returns default responses if the script doesn't exist or
if the script doesn't define a function that handles that particular API call.
The entire system has been implemented using Object::call() and its
ability to switch to the script instance to handle the API call if the
script exists. Look for VersionControlEditorPlugin::_initialize() for
the essential API setup.
