Expose OverrideButton.

[martiandweller]

I'm working on a mod that automates the Farmer's actions, including movement. The animation breaks when I try to move the character with SetMovingUp() and similar methods. I believe this is because the Game1.UpdateControllerInput() method Halt() the character and resets an animation if there is no input.

if ((!moveUpHeld && !moveRightHeld && !moveDownHeld && !moveLeftHeld && !player.UsingTool) || activeClickableMenu != null) { player.Halt(); }

This PR exposes already existing OverrideButton method to the mod API.