Add "Reaction" to mash triggers, intergrated with reaction time

[asimon-1]

From Senator WTFinland in discord:

Development idea:

Add "reaction" as one of the triggers for mashing and then a slider for reaction time.

As in, have the CPU start input things when the player presses anything after save state load.

And reaction time slider so we can test the different outcomes from opponents reacting differently. Being able to set the reaction to the average human reaction + input lag of 18f would be really good.