* Support multiple optimizers

* minor refinement

* improve unit tests

* minor fix

* Update unit tests for resuming or saving ckpt for multiple optimizers

* refine docstring

* refine docstring

* fix typo

* update docstring

* refactor the logic to build multiple optimizers

* resolve comments

* ParamSchedulers spports multiple optimizers

* refine docstring

* RuntimeInfoHook supports printing multi learning rates

* resolve comments

* fix typo

* [Refactor] Add batch_idx to hook input.

* update

* [Refactor]: Change scheduler to param_scheduler

* [Fix]: Fix UT of param scheduler hook

Co-authored-by: Your <you@example.com>

* [Fix]: Change after inter and epoch to after train iter and epoch

* [Fix]: Add new UT to param scheduler hook

* [Fix]: Change the type of runner in docstring to Runner

Co-authored-by: Your <you@example.com>

* [Feature]: Add param scheduler hook

* [Fix]: update docstring and add assert_call to UT