Add PRIVATE_FLAG_CONSUME_IME_INSETS

It is a flag to indicate that the window consumes the IME insets. This
makes windows below unable to receive visible IME insets.

Fix: 311026631
Test: atest InsetsPolicyTest
Change-Id: I1ad10ce6ef41d14989de2fd4e188acd8b9c283d5
5 files changed