Fix Keyboard shown after force stopped app package

CL[1] add a check in IMMS#hideCurrentInputLocked to
ignore hide request when the current client or the current
input session is null for preventing switching IME may have
unexpected keyboard hidden when focusing the same window to
start input case.

A regression happens when forcing stop the app with focusing a editor
and show soft-keyboard, because the hide request ignored as the above
mentioned, so keyboard will be shown after the next input connection
started since the mShowRequested didn't set to false by hidden request.

As CL[2] uses sameWindowFocused to check all possible hide current
keyboard call places in startInputOrWindowGainedFocusInternalLocked to
hide soft-keyboard only when the window focus changes, so we should
revert the check in IMMS#hideCurrentInputLocked to fix this keyboard
visiblity issue.

[1]: I37ae6e30d1de581ba15131c2a90396b3a522a4d6
[2]: I20e8076acc5fec3c055af0740e2e2a64b1fb6f0d

Fix: 171009669
Test: atest KeyboardVisibilityControlTest
Change-Id: I92accb513b728820a3043b365aa5fa4f3a1a34a5