Remove mouse when gamepad in use

[jukibom]

The mouse is currently visible and also required (along with esc on keyboard) for text entry fields:

ISteamUtils Interface provides the ShowFloatingGamepadTextInput and FloatingGamepadTextInputDismissed_t member function which allow you to open the on-screen keyboard and also be notified when it is closed. The following text fields do not trigger the on-screen keyboard: in game chat, changing the amount of players for a server, and inputting a seed and the dev option as well.

(valve feedback)