[long-tx-api] Refactor: WriteSet is now kept as a ValueType
[jvstm-common] Bug Fix: Generate correct slot name for collection boxes
[long-tx-api] Don't store the contents in a String, store them in a JsonElement instead
[jvstm-common] Support LongLivedTransactions using direct JsonElement
[long-tx-api] Performance Improvements
[long-tx-api] Don't duplicate the WriteSet map, instead put the entries in the new map.

  * Also allow for the Maximum WriteSet size to be configured
[jvstm-common] When Aborting a Long-Lived Transaction, also abort the underlying