Add ALLOW_SLIPPERY_TOUCHES permission

This permission allows the app to use FLAG_SLIPPERY. This means, windows
of the app that has this permission can let touches slip out when the
finger moves out of the window bounds.

Bug: 157929241
Bug: 206188649
Test: atest FlagSlipperyTest
Change-Id: I9ccdfd298f32c36b9c4da68c2e9c355c97dc7593
diff --git a/packages/SystemUI/AndroidManifest.xml b/packages/SystemUI/AndroidManifest.xml
index dde0a19..f57d02c 100644
--- a/packages/SystemUI/AndroidManifest.xml
+++ b/packages/SystemUI/AndroidManifest.xml
@@ -121,6 +121,7 @@
     <uses-permission android:name="android.permission.SET_ORIENTATION" />
     <uses-permission android:name="android.permission.DISABLE_KEYGUARD" />
     <uses-permission android:name="android.permission.MONITOR_INPUT" />
+    <uses-permission android:name="android.permission.ALLOW_SLIPPERY_TOUCHES" />
     <uses-permission android:name="android.permission.INPUT_CONSUMER" />
 
     <!-- DreamManager -->