Enable IME Insets flag

Brave new world! Flips the flag to enable new Insets for IME only.
Flip it and let it roll :D

Bug: 111084606
Test: atest CtsWindowManagerDeviceTestCases -- --module-arg
 CtsWindowManagerDeviceTestCases:include-annotation:android.platform.test.annotations.Presubmit
 --module-arg CtsWindowManagerDeviceTestCases:exclude-annotation:androidx.test.filters.FlakyTest
 atest android.view android.inputmethod android.inputmethodservice com.android.server.wm
Change-Id: I6d2b3086a21dee5865e50766be571edfd56de489