New saving/loading behaviors to fix bugs related to saving

[moonysolari]

Tested with casual gameplay, both before and after restarting the game and Peacock.

New saving/loading behaviors

• When saving,
  • The incoming data is checked against several criteria to reject unwanted requests.
  • Information about the saved sessions and the slot they correspond to are stored in a new field Saves in user profiles.
  • The contract session gets stored to a file in contractSessions. The filename is in the format of slot_token_sessionID.json.
• When a save slot gets overwritten,
  • The Saves field of the user is updated with new information.
  • The file that keeps track of the overwritten session is deleted.
  • A new file is created for the newly stored session.
• When loading,
  • Peacock will load any file with the given token and sessionID in the filename, ignoring the slot name.

Other changes

• The list of SaveFiles received from /authentication/api/userchannel/ProfileService/UpdateUserSaveFileTable is correctly processed, such that the one with the latest timestamp is used instead of the last one in the list.
• The naming convention of the files in contractSessions is changed. They now have the slot name prepended.
• Several variable were renamed in components/databaseHandler.ts to avoid confusion. There were previously named sessionids but none of them were IDs of a session.
• saveSession and loadSession were moved to components/profileHandler.ts.
• Removed unused property PeacockCChild in user profiles.
• Added some debug info for related functions.

Issues likely fixed (need testing)

• Wrong token and sessionID saved when game saves #72 .
• Any problem with loading an autosave, as their sessions were completely unsaved previously.
• Save/load exploit to spam leaderboards with impossible time records.
• Getting incorrect scoring and/or rating after loading a Peacock save.
• Other issues related to saving/loading.

[RDIL]

Mainly just consistency stuff, but one nullability concern.

In general, we use new Error instead of Error, and have a space before and after if statements, unless it starts/ends a block.

[RDIL]

I assume you've tested this already, so LGTM