[Request] Implement a way to inhibit the screen saver

[A6GibKm]

This is already covered by gamemode (See #146), but users might want to do this without gamemode when playing a game.

See the https://docs.gtk.org/gtk3/method.Application.inhibit.html method, and lutris/lutris#4150 for a reference implementation.

[mirkobrombin]

Thanks for reporting and for the documentation!

[n3thshan]

hi what is the progress on this? its being two years! i am playing a visual novel in windowed mode and the display dimming is so annoying as there is not a lot of keyboard/mouse/controller input with these kinds of applications. Also i know gamemode can control this behaviour but i dont want to use it because its a visual novel and i dont want my laptop draining power due to changes made by gamemode needlessly.