Parking brake realistic mode

[remenkemi]

When in realistic mode, setting the parking brake still pulls the lever up and causes takeoff config warnings and the parking brake eicas message but doesn't brake.

Remember that the parking brake is just a physical lock that holds the pedals down, so if the pedals are not being pushed down while engaging the parking brake, the lever should just flip back to off rather than staying in the engaged position. zibo simulates this correctly.

so basically, when i press v (default parking brake keybind) it should always lift the parking brake lever. Whether it stays up or goes back down depends on whether the brakes are pressed. if not, it should just physically flip back to disengaged and not latch on engaged.

Additionally, in realistic mode, pressing the toe brakes while the parking brake is engaged should disengage it

I will verify all this on my 777 flight and let you know.