Additional save related panorama events

[vrad-exe]

These are intended for use by the save indicator HUD element:

• Add an event for when the save operation finishes
• Add a fourth value to the SaveType enum for "dangerous" autosaves, so these can be differentiated from regular autosaves (technically this is already doable by checking the save name, but this feels more proper)
• Add an event for when a dangerous save is marked as safe
• Add an event for when the game tries to save, but fails due to save_disable or map_wants_save_disable

[iamsirenstorm]

So we have 2 Panorama APIs that interact with save files. One was brought in from Revolution (GameSavesAPI), and another WIP one was brought in (SaveRestoreAPI) and they both currently co-exist in P2CE. I've decided to melt these two together, removing SaveRestoreAPI and putting its functions into GameSavesAPI. SaveType is from SaveRestoreAPI and will no longer exist. There are already different events fired for the different save types, so the 2nd point is not necessary anymore. For everything else, they've been added.

See StrataSource/pano-typed/pull/56 for the changes and if you have any opinions/feedback.