Explore deduping in TxLog

TxLog could dedupe objects. For example in the case where the TxLogs contains two different Bytes objects with equal content, it could just maintain a pointer to one. Not sure if this would cut down on what kryo serializes.

Locate TxLog and the Kryo serialization path first; compare how equal-content Bytes objects are represented and serialized. Done would require a decided deduplication design and evidence that it reduces serialized data, but the issue names no files or tests.

Written by the indexing model from the issue text.