bw_gen_fn return maybe (#5455)

* modified SetInputArgModifyFn

* Delete the CHECK changes in the assign_op.cpp file

* Format

* Modified the OutputArgModifyFn interface

* add return

* maybe error stack from CheckAndConstructOp to OutputArgModifier callback function

* maybe error stack from CheckAndConstructOp to OutputArgModifier callback function

* OutputArgModifier return maybe part_1

* maybe error stack from CheckAndConstructOp to OutputArgModifier callback function

* input_arg_modifier return maybe

* gen_bw_fn return maybe

* bw_gen_fn return maybe

* fix bug: return Maybe without JUST

Co-authored-by: aishangjj <702572275@qq.com>