Qt/Overlays: Add sound effect manager

[Megamouse]

• Adds Menu -> Manage -> Sound Effects
• This allows you to import and remove sound effects for the RPCS3 overlay (a feature that already existed in secret)

It's very simple but I'm not in the mood for making it pretty:

[schm1dtmac]

Brief question: Is automatic RCO extraction a viable option at all to just pre-populate the sounds with the PS3 FW ones? IIRC the naming scheme was meant to be the same, so unless there's a technical/legal holdup I'd say that an option for that in the GUI would be handy.

[Megamouse]

Brief question: Is automatic RCO extraction a viable option at all to just pre-populate the sounds with the PS3 FW ones? IIRC the naming scheme was meant to be the same, so unless there's a technical/legal holdup I'd say that an option for that in the GUI would be handy.

The original idea was to take it from there automatically, but since it's in various containers that we don't extract I added the custom way.
Maybe I can try another time