Implement save backfill feature

[Akuukis]

For existing saves, Stellaru loads only one save file and skips/ignore the rest. I think it's a bug because the UI doesn't let me select a specific save file but only "a save" (aka folder), where I'd assume it would load the whole folder like the other stellaris-dashboard does.

My last MP session has lots of intermediary saves every couple of years (see screenshot), and several autosaves. If Stellaru could load all saves, that would allow to investigate past play-throughs, but more importantly would enable to quickly test/preview the tool without spending lots of time to play another play-through.

[benreid24]

The idea to do this honestly never crossed my mind. I think this should be a separate action that users can opt to do, maybe a 'Backfill' button on the frontend. Loading a save may take some time, and loading many saves could take a very long time. There's also the issue of players save-scumming, which is fine so long as the backfill option is a discrete action that players initiate themselves. I think this would be fun to implement.