Correctly close IME keyboard if Calculator is launched

To reproduce eg open from a window which already has IME opened directly
the calculator (eg from SlimRecents or from Google Search). Result is that
the keyboard will stay open.

Mainly it is due to using the FLAG_ALT_FOCUSABLE_IM flag which keeps the keyboard
open if the window before had FLAG_NOT_FOCUSABLE set.

To resolve it use SOFT_INPUT_STATE_ALWAYS_HIDDEN flag to keep it permanently disabled. As
well to be sure close any soft input method on Calculator launch.

Change-Id: I0248fd269ab1b0d620e424f86b94beff18c6656e