Split index_op, elemwise_unary_op_trig operator into smaller pieces

[stu1130]

Description

Split the bigger object file index_op.o which is generate by indexing_op.h, indexing_op.cc, indexing_op-inl.cuh and second bigger object fileelemwise_unary_op_trig.o which is generated by elemwise_unary_op_trig.cc and elemwise_unary_op_trig.cu into smaller pieces like #15922.
It helps compiler compile the files parallelly and solve out of heap space error when the size of object files breach the heap space again in the future

[frankfliu]

@mxnet-label-bot add [feature request, operator]

[DickJC123]

Do you have examples showing the CI failing currently on these files?

[stu1130]

Hi @DickJC123 I didn't have CI failure. It's running fine. But as the numpy project continue adding more operators, I would expect those two files will trigger the error again.