[Bedrock] Button to expose mouse mid-game

One of the biggest hurdles with the current UI implementation in the Scripting API is that the creator isn't able to assign keys for opening the UI, due to the absence of such keys in the different platforms the API will be on. One of the solutions would be to have a dedicated button (only available with scripts enabled) that would expose the mouse/controller pointer mid-game so PC/Console players can interact with custom HUD UI