Move ImmersiveModeConfirmation to system UI (4/n)

This change move the WM side immersive mode confirmation window to the
system UI side. The major change of the immersive mode confirmation mode
to accomodate system UI side logic includes:

1. Power key panic is handled purely in DisplayPolicy, with a tracking
   of existance of the immersive confirmation window.
2. Introduce another layout params private flag to identify the
   immersive mode confiramtion mode.
3. CLIENT_* flags handling.
4. Vr and release handling, and most of the settings and display change
   handling moved to system UI.
5. Updated the text color of the window to match the themed background
   color.

Introduce CLIENT_IMMERSIVE_CONFIRMATION flag to control whether client
or the server side of immersive confirmation window shall be used. The
flag will only be in effect if the CLIENT_TRANSIENT flag is not true,
otherwise, the client side confirmation window will always be used.

Bug: 277290737
Test: build
Test: enable CLIENT_TRANSIENT and check the existance of the immersive
mode confirmation window.

Change-Id: I99f6097cb867f9808aecf4c7105289550001f452