Journaling and Snapshot improvement

[SimonVillage]

On restart the engine throws an error that the file already exists. The following should solve this problem.

Comment this line:

https://github.com/mzheravin/exchange-core/blob/eb926cb7779c8fdf0571ed2300f53a8be3606452/src/main/java/exchange/core2/core/processors/journaling/DiskSerializationProcessor.java#L366

Add filesCounter++; to:

https://github.com/mzheravin/exchange-core/blob/eb926cb7779c8fdf0571ed2300f53a8be3606452/src/main/java/exchange/core2/core/processors/journaling/DiskSerializationProcessor.java#L434

Snapshot kind of works but it would be great if the engine would read the values from the main log and set the snapShotId in InitialStateConfiguration.lastKnownStateFromJournal() automatically if not provided.

The dumpId() when generating a snapshot should automatically increase if not provided.

This would allow the engine to restart and to read the last snapshot automatically as well as writing a snapshot with the next id without providing it.

@KabDeveloper you have been working a bit on this and provided a PR to fix a different issue with the journaling. Would you be interested to provide a PR for this too? Otherwise I would look into it but I usually don't do much Java and would like to avoid making any mistakes.