Add data transform notion for persistence

[grofit]

Currently we have focused on the game data that is required to create and run a game, such as item templates, class templates etc.

However not much formality or guidance has been given on how to store the runtime aspect of data.

For example currently an item at runtime contains information on the items template, how many instances it has, any modifications etc. When we go to persist that item really all we need to know is what item template Id it is, and how many of them we have, with any custom meta data stored with it, this reduces data storage size and also keeps a separation of dynamic runtime data and static game data.

For now it's assumed we can add an interface for data transforming from one type to another which can probably live within the existing data project and then add storage classes and helpers to relevant libs like genres etc.

The overall idea would be that at point of loading or saving the game data the user can just pass the data through all the transformers (or maybe create a pipeline using persistity etc).

[grofit]

A lot of this has been done within the Genres lib under the Persistence namespace, however it could still be made simpler still going forward.