* controller: use Back as the touchpad click on pads without a touchpad
Gamepads without a touchpad (Switch, Xbox, 8BitDo, ...) cannot click it, so
games that require the touchpad can't be played with them. The keyboard
already emulates it (Backspace/Tab); gamepads had nothing.
For SDL_GAMEPAD_BUTTON_BACK on a pad that reports no touchpads, report
PAD_BUTTON_TOUCH_PAD plus a finger at the centre of the touchpad. Pads with a
real touchpad are unchanged.
Fixes#1298
* controller: establish touch before fallback click
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Co-authored-by: nmzik <Nmzik@mail.ru>
