Remember window position & size

[PiKeyAr]

At the moment the Mod Manager doesn't save its window state (maximized or not), window size and position upon exiting, so restarting the program resets to default position and size. This becomes an issue when the default position and size are difficult to use, for example with the current design the Mod Manager's controls don't fit the screen at 1920x1080 with 150% scaling so it needs manual adjustments on every startup.

[Sora-yx]

The last update should now save the size when you click on save and load it on startup. I haven't added position yet, since I remember an issue with it from the old Manager where on a rare case, the window could become unavailable, as if it was offscreen. I do not know if that issue would be on WPF, this would require more tests first, but either way, I figured out size should be the most important part for now.