Add QA fine-tuning script

[a1378328591]

Add fine-tuning script for Question Answering (QA) model.

[Ravenyjh]

we may need to add a new decision entry to implement an automatic distribution script mechanism, such as automatically adapting dataset to fine-tuning_qa.py. However, for greater versatility, we still needs some time to sort out the logic of this part, so the adaptation may not be completed in the short term. We will continue to follow up and optimize it, and we’ll update you as soon as there’s any progress!