[SPARK-3660][STREAMING] Initial RDD for updateStateByKey transformation

SPARK-3660 : Initial RDD for updateStateByKey transformation

I have added a sample StatefulNetworkWordCountWithInitial inspired by StatefulNetworkWordCount.

Please let me know if any changes are required.
I think the ordering of records in each batch tripped the unit test. You can try out this function `assertOrderInvariantEquals` . Its defined in the same file.