Don't store values when loading them

[KoBeWi]

I noticed some editor parts will read project metadata config and immediately write it to the same value, which is a faulty logic. This PR fixes all cases I could easily find.

[KoBeWi]

I pushed some more changes, but I wonder if it can be handled better.

[Mickeon]

Indeed, that boolean initializing feels consistent across the board. There's a pattern.

[akien-mga]

Seems good for now, but we can indeed think about how to make this pattern more explicit and obvious to contributors.

[akien-mga]

Thanks!