Bert qa sample's tests errors 

Currently, the Bert qa sample's tests are written in java, we have to change it to Kotlin and also there are some compilation errors that are needed to be resolved

Test Link: https://github.com/SunitRoy2703/Tensorflow-lite-kotlin-samples/tree/master/bert_qa/app/src/androidTest/java/org/tensorflow/lite/examples/bertqa 