Fix quickloading

[angleKH]

Summary

Bugfixes "Restored quickload to working order"

Purpose of change

This PR fixes the quickload function (currently crashes) and enables it in release builds under the debug menu, and adds the same warning as the "Quit without saving" option. This would also be especially helpful for development.

This also happens to fix #38557.

Describe the solution

Rather than attempting to call the functions to load the game directly, as the current implementation does, this simply loads the world as if the user exited to the menu and immediately loaded the world again. This means the cleanup code from exiting will also run, unlike the current implementation which is missing some.

For this PR, on quickloading, the current world and player save is queued to load the next time the main menu is entered. Then the game exits to the main menu but loads the world immediately. Because of this the data files still need to go through the loading/validating process, but this is also the case for the current implementation.

The cli option --world has also been changed to use this queue rather than being part of the main loop as an if statement.

Describe alternatives you've considered

Loading the world again without simulating exiting and loading the world from nothing would be best, but is infeasible. I could not get it to work. This would also likely add a lot of duplicated code from the necessary cleanup.

Before using the main menu, I also tried using the current implementation of the cli --world option's method to load the world (g->load in the main loop before menu) after running cleanup code. This worked, but segfaulted after a couple of quickloads. This also implies that there may be some problem with the current implementation of the cli --world option.

Testing

Tested only on Linux.

• Tested quickloading several times.
• Tested with the same world.
• Tested after switching between different worlds.
• Tested with worlds containing multiple characters to ensure the correct character was quickloaded.
• Tested quickloading after loading a world with the cli --world option.

Additional context