Migrate form v0.x to v1.x

1. Check the interfaces change:

• IEnforcerProvider

public interface IEnforcerProvider
{
    // Before
    public Enforcer? GetEnforcer();
    // Now
    public IEnforcer? GetEnforcer();
}

• ICasbinModelProvider

public interface ICasbinModelProvider
{
    // Before
    public Model? GetModel();
    // Now
    public IModel? GetModel();
}