Add option to only format on hotkey in case automatic saving is used

[3ter]

I'm using autosave which is not really usable with format on save triggering automatically as well.

After a quick search I couldn't find a way to distinguish between auto and manual saves unfortunately so I suppose the only option would be to introduce a hotkey (which could be the same as for saving the script) and switch off gdformat on (auto) save.

Or do you think in that case I should use https://github.com/Daylily-Zeleen/GDScript-Formatter? I don't really understand why there are two plugins, but I suppose this could be the key difference.