Use inputtarget to check for insets controller

Was using just the window target, but we need to actually use
the inputmethodinputtarget since that has an activity that can
actually be checked for split-screen mode.

Additionally, we need to force-update the Wm configuration
because we skip doing so when divider is "hidden" by keyguard.

Bug: 159457357
Test: open split with pip running. Open keyboard in secondary,
      lock screen, then unlock.
Change-Id: Idbc0c3b90c18a55cc664c6958546994cbb8549ee