Replace Snapshot invalidate logic with WriteSet check for txn conflict detection

Issue with concurrent writes on partitioned table:
Concurrent writes on different partitions should execute in parallel without issues. They acquire a shared lock on table level and exclusive write on partition level (hive.txn.xlock.write=true).
However there is a problem with the Snapshot validation. It compares valid writeIds seen by current transaction, recorded before locking, with the actual list of writeIds. The Issue is that writeId in Snapshot has no information on partition, meaning that concurrent writes to different partitions would be seen as writes to the same non-partitioned table causing Snapshot to be obsolete.