Export As Image when saving map file

I have a folder of small Tiled files that form components of a larger map. I'd like to save an imagerep of these whenever I make a change to the Tiled file. This would give me a gallery of components without having to open them all up and browsing.

I'm on the Mac so I imagine this as a toggle under the File menu to "Export as Image when Saving". The export could use settings stored in prefs or simply use 100% zoom with only visible layers.

Start at the File menu and the save workflow to determine where an “Export as Image when Saving” toggle would fit. Check how the existing image export uses zoom and layer visibility, then verify that saving a Tiled file produces the corresponding image when the option is enabled.

Written by the indexing model from the issue text.