Get group name dynamically when generating permission definitions

[wakuflair]

 public class XXXPermissionDefinitionProvider : PermissionDefinitionProvider
    {
        public override void Define(IPermissionDefinitionContext context)
        {
            var xxxGroup = context.AddGroup(XXXPermissions.GroupName);
            ...
        }
    }

Take above code as example, the group name "xxxGroup" may be changed by developers. CLI should parse the Provider class, and retrieve the name from the existing statement.