• 정확한 리스너는 없지만, screenHeight와 keypad 를 계산해서 감지 가능

private fun setKeyboardListener(){
    binding.root.viewTreeObserver.addOnGlobalLayoutListener {
        val rec = Rect()
        binding.root.getWindowVisibleDisplayFrame(rec)
        val screenHeight = binding.root.rootView.height
        val keypadHeight = screenHeight - rec.bottom

        if (keypadHeight > screenHeight * 0.15) {
            viewModel.showKeyboard()
        } else {
            viewModel.hideKeyboard()
        }
    }
}