Add toggle fast forward binding

[kunal-sharda]

Adds a separate Toggle Fast Forward global binding while preserving the existing hold and fast forward action. References OpenEmu/OpenEmu#4886

Additions:

• adds a new global binding identifier and binding name
• exposes Toggle Fast Forward in Controls
• latches fast-forward in OESystemResponder using separate held/toggled state
• leaves the existing core fast-forward runtime behavior unchanged

Manual tests:

• bind Toggle Fast Forward in the settings
• press once: fast-forward stays enabled
• press again: returns to normal speed
• existing Fast Forward binding still works as hold
• mixed hold/toggle interactions behave correctly

Tests: no automated tests added. I'm willing to add if this is an ask.

[kunal-sharda]

I know there was already a fast forward commit with a sliding scale, but I wanted a toggle locally. Hopefully this can be helpful? Let me know if I need to change anything, thanks!