Clean up hideLw and showLw of WindowManagerPolicy#WindowState

Move all usages from PhoneWindowManager to DisplayPolicy.
And the unused interfaces are also removed: setAodShowing,
isStackVisibleLw, applyKeyguardPolicyLw, getDisplayId,
isInputMethodWindow.

The condition of "hideDockDivider" is removed from
shouldBeHiddenByKeyguard because it isn't related to keyguard
and the management of divider should be handled by
SplitScreenController in WM shell.

Bug: 163976519
Test: WmTests CtsWindowManagerDeviceTestCases presubmit

Change-Id: I67a9fbb3b03b63044dc84630473f8f639444d0b3