Qtfred save shine effect

[MjnMixael]

Adds the requested UX feedback on save with a soft animated shine that sweeps left to right on the status bar. This is in addition to the last saved timestamp being displayed.

[JohnAFernandez]

My only suggestion is that one second might be too long, compared to how long the save actually takes, but that's pretty subjective.

Oh also, users may want to turn it off in preferences, but we can do that later.

[MjnMixael]

My only suggestion is that one second might be too long, compared to how long the save actually takes, but that's pretty subjective.

Oh also, users may want to turn it off in preferences, but we can do that later.

To my eyes, 500ms was too short and made it feel sharp and unclear. 1 second was nice and smooth.

I considered preferences but I would advise against it. It's not intrusive and provides a valuable signal. I would want to avoid packing preferences with such minor things. This is an editor, not the game itself.