Replace DataTemplateManager simulation component with a globalscript, refs #4868.
Removes the serialization of JSON files, shrinking savegame files and rejoin states sent across the network, refs #3834, #4239, #3909, rP18100.
Removes the AI C++ code to read JSON files from rP13225 since the AI can now use the globalscript.
Allows the AI to read Aura templates and removal of GUIInterface code to improve performance.
Serialization of the JSON objects in other simulation components was removed in r20606 / D1109, r20610 / D1130.
Serialization removal planned by sanderd17
AI part proofread by mimo
Simulation part proofread by bb
Discussed with Itms on irc
Differential Revision: https://code.wildfiregames.com/D1108