Bind quick load state to F4 instead of F2 because both F1 and F2 are next to each other on the keyboard

[ghost]

I have already said this in the bottom of the last comment of #1119:

About quick load state I prefer by default to bind it to F3 and not F2, exactly like how it is already done on PCSX2, because both F1 and F2 are next to each other on the keyboard and this can also happen that the user will accidentally press F2 instead of F1 when he or she is going to save his or her progress to a quick state file and think about what he or she will do next in the PS1 game that he or she is playing with PCSX-Redux before the accident. F3 is further away from F1 than F2 on the keyboard decreasing both the chance and probability for a mistake. Personally I will prefer F4 for quick load state, unlike what PCSX2 does, to completely eliminate both the chance and probability for a mistake because F4 is even further away from F1 than F3 on the keyboard.

But I think that this idea needs a separate discussion since #1119 talks about the global state of PCSX-Redux while this discussion talks about the quick state of PCSX-Redux. These are two different topics so each need a separate discussion.