Change 'disable hardware keyboard' to 'show input method'

Previously it implied that the hardware keyboard would be disabled,
but really the toggle would just enable showing the IME even if a
hardware keyboard was present. Changed the string and swapped the
semantics to be more clear about the behavior.

Bug: 14066881
Change-Id: I9c8a7eb98b5277f1d09cc19fa7402e9b4cf51d92