Various Subscene Fixes

[Areloch]

• Update levelAsset creation so it can be flagged to be creating a subScene preemptively, improving workflow when creating a SubScene level asset 'in place' via the inspector.
• Fixed issue of creating new SubScene using the full level template instead of a blank level file
• Fixed subScene inspector field handling so clicking the create new will mark the 'in place' created level asset as a subscene appropriately
• Changed up persistenceManager logic when parsing objects out - especially with specialty fields - to use Strings instead of const char* to simplify memory juggling and improve stability
• Rolled back specialty array field outputs for decal roads and convex shapes to have the field names in the output again
• Added sanity check for MeshRoad's when writing out via specialty array field to ensure there are profile nodes before trying to write any
• Added sanity check to avoid pointlessly writing out meshroad and river position field into subScene file as it could cause a transform double-up and cause them to move when loading from a subscene