Reworked load_save to support server mods in replays and saved games (first pass)
Reworked load_save to support server mods in replays and saved games (first pass)

- reworked sequence of events to support server mods in replays and
saved games:
 - wait for replay to fully load with server mods info
 - process replay config
 - wait for client to connect and send first heartbeat from
replay_loading
 - send mods info to client
 - wait for send_mods request from client (allows client to mount
missing companion mods)
 - send mods to client with downloadModsFromServer
 - wait for mod_data received
 - send any cooked files to memory mount
 - wait for memory_files_received
 - generate armies
 - create sim from replay
 - move to playing state
- added mods_info client message sent when replay is fully loaded and
client sends heartbeat from replay_loading
- added send_mods handler when client is ready to download server mods
and any cooked files
- added mod_data_received handler when server mods have been download
and mounted on client

UberEnt/pa-server-script