* fix build multiple scheduler

* add new unit test

* fix comment and error message

* fix comment and error message

* extract _parse_scheduler_cfg

* always call build_param_scheduler during train and resume. If there is only one optimizer, the defaut value for sheduler will be a list, otherwise there is multiple optimizer, the default value of sheduler will be a dict

* minor refine

* rename runner test exp name

* fix as comment

* minor refine

* fix ut

* only check parameter scheduler

* minor refine