InputBind: Sync / Return Code

[DeltaGW2]

Currently all input bind handlers are called async if they are reached. Meaning whatever was last input is always intercepted and not relayed to the game.
This holds true even if the InputBind handler returns early such as for example if it's not supposed to process while the chat is active.

Goals:

• Add a return code to signal if processing should continue.
• Make the call synchronous to allow for a return code to begin with.

Need to verify no negative impact on performance. Potentially cache the keycode until a return is reached?