Save without references for godot4 branch

[pcen]

cherry-picked https://github.com/C7-Game/Prototype/pull/425 and added some fixes to make it work on the godot4 base branch

I will also cherry-pick the save game code path as a separate PR.

[WildWeazel]

@pcen bump... if you can do something else with those saves and reformat if you want to now, then I think we're good to merge this