[PATCH] Serialize the data in DataTemplateManager to avoid OOS on rejoin

[Itms]

The data in DataTemplateManager is only read from the disk so we don't serialize it. However, on rejoin, if a template had been loaded by the host, the next time this template is loaded, the guest will load a new JS object (which has the same content as the host's but it's not the same object).

Upon serialization, the objects will have different backrefs on the two instances, leading to a difference in the binary simstates.