loading simplification

Hello,

When loading a save file, it would be convenient to directly display the saves corresponding to the current game mode (campaign, scenario, multiplayer). Indeed, when playing a game mode, we almost always load a save that corresponds to that mode and not another. And the rare times when this is not the case, we'll simply have to go to the main menu first.

Additionally, the warning window indicating that the current game will be lost could be supressed and instead add a message next to the save file list, and add the option to cancel and return directly to the ongoing game, similar to how it works when accessing the options.

Regards.